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X-WR-CALNAME: BIU, Condensed Matter Resnick seminar
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BEGIN:VEVENT
UID:calendar:4819:field_when:0:0
SUMMARY:The orthogonal semi-metal: deconfined criticality and Fermi-surface \n
reconstruction without translational symmetry breaking.
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200521T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200521T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4819
LOCATION:zoom
DESCRIPTION:Speaker: Snir Gazit\n
\n
Abstract:\n
Gauge theories play a central role in the theoretical description of \n
unconventional phases of matter that go beyond the standard paradigms of \n
quantum statistical mechanics. While in high-energy physics\, gauge fields \n
correspond to fundamental particles\, in condensed matter theory they are \n
typically emergent and are invoked as an effective description of the \n
low-energy degrees of freedom. Notable examples include spin-liquids\, doped \n
Mott insulators\, and the fractional Hall effect\, among others. In my talk\, I \n
will present a sign-problem free quantum Monte Carlo study of a lattice model \n
hosting 'orthogonal' fermions coupled to an Ising-Higgs gauge theory. Our \n
model provides a simple yet highly non-trivial example of electron \n
fractionalization\, which\, crucially\, remains numerically tractable. We \n
uncover a particularly rich phase diagram arising from strong correlations \n
between gauge and matter fields. In particular\, we find that in the \n
background of pi-flux lattice an orthogonal semi-metal (OSM) forms with \n
gapless Dirac fermion excitations. With tuning of parameters\, the OSM \n
undergoes a confinement transition\, in which symmetry breaking and \n
confinement are coincident. We construct a field-theoretical description of \n
the transition involving condensation of a matrix Higgs field. The critical \n
theory is predicted to sustain an emergent and enlarged local (gauge) and \n
global symmetries. We provide numerical evidence supporting this \n
prediction. We also find that the physical (gauge-neutral) spectral \n
function in the OSM phase comprises four fermion pockets\, which smoothly \n
evolve to a 'large' Fermi-surface upon approach to a Fermi liquid phase. \n
The reconstruction of the Fermi-surface does not involve any form of \n
translational symmetry breaking\, in violation of the Luttinger sum-rule.\n
\n
\n
\n
Link to zoom [1]\n
\n
\n
[1] https://zoom.us/j/94772812480
END:VEVENT
BEGIN:VEVENT
UID:calendar:4818:field_when:0:1
SUMMARY:Boundary Obstructed Topological Phases
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200514T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200514T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4818
LOCATION:zoom
DESCRIPTION:Speaker: Raquel Queiroz\n
\n
Abstract:\n
Symmetry protected topological (SPT) phases are gapped phases of matter that \n
cannot be deformed to a trivial phase without breaking the symmetry or \n
closing the bulk gap. Here\, we introduce a new notion of a topological \n
obstruction that is not captured by bulk energy gap closings in periodic \n
boundary conditions. More specifically\, given a symmetric boundary \n
termination we say two bulk Hamiltonians belong to distinct boundary \n
obstructed topological phases (BOTPs) if they can be deformed to each other \n
on a system with periodic boundaries\, but cannot be deformed to each other in \n
the open system without closing the gap at at least one high symmetry \n
surface. BOTPs are not topological phases of matter in the standard sense \n
since they are adiabatically deformable to each other on a torus but\, \n
similar to SPTs\, they are associated with boundary signatures in open systems \n
such as surface states or fractional corner charges. In contrast to SPTs\, \n
these boundary signatures are not anomalous and can be removed by \n
symmetrically adding lower dimensional SPTs on the boundary\, but they are \n
stable as long as the spectral gap at high-symmetry edges/surfaces remains \n
open. We show that the double-mirror quadrupole model of [Science\, 357(6346)\, \n
2018] is a prototypical example of such phases\, and present a detailed \n
analysis of several aspects of boundary obstructions in this model. In \n
addition\, we introduce several three-dimensional models having boundary \n
obstructions\, which are characterized either by surface states or fractional \n
corner charges. We also provide a general framework to study boundary \n
obstructions in free-fermion systems in terms of Wannier band representations \n
(WBR)\, an extension of the recently-developed \n
\n
band representation formalism to Wannier bands. WBRs capture the notion of \n
topological obstructions in the Wannier bands which can then be used to study \n
topological obstructions in the boundary spectrum by means of the \n
correspondence between the Wannier and boundary spectra. This establishes a \n
form of bulk-boundary correspondence for BOTPs by relating the bulk band \n
representation to the boundary topology.\n
\n
\n
\n
Link to seminar recording [1]\n
\n
\n
[1] https://biu365-my.sharepoint.com/:v:/g/personal/ruhmanj_biu_ac_il/ESBch-MyFKVOlWZ3UEehoCQBllvOnWUNHBQJSQR-1ZL7SA?e=hBgsOA
END:VEVENT
BEGIN:VEVENT
UID:calendar:4812:field_when:0:2
SUMMARY:Higgs amplification in non-equilibrium K3C60
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200507T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200507T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4812
LOCATION:zoom
DESCRIPTION:Speaker: Daniel Podolsky\n
\n
Abstract:\n
The quest for new functionalities in quantum materials has recently been \n
extended to non-equilibrium states. In the context of superconductivity\, \n
examples have included the generation of transient superconductivity above \n
the thermodynamic transition temperature\, the excitation of coherent \n
Higgs-mode oscillations\, and the optical control of the interlayer phase in \n
the cuprates. In this talk\, I will propose that a prompt quench into a \n
transient superconducting state from a metal induces large Higgs fluctuations \n
of the order parameter\, and will demonstrate that these fluctuations give \n
rise to the amplification of light at frequencies below the superconducting \n
gap. I will show new measurements on K3C60\, in which these predictions are \n
verified experimentally.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4806:field_when:0:3
SUMMARY:Spectral Gaps and Midgap States in Random Quantum Master Equations
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200423T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200423T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4806
LOCATION:zoom
DESCRIPTION:Speaker: Dror Orgad\n
\n
Abstract:\n
How nonequilibrium systems relax to steady states is a central topic in \n
many-body dynamics. Of particular interest are universal features of such \n
dynamics. In this talk I will discuss the decay rates of a chaotic quantum \n
system coupled to noise. I will do so within a model where the Hamiltonian \n
and (possibly) the system-noise coupling are described by random N x N \n
Hermitian matrices. The focus will be on the spectral properties of the \n
resulting Liouvillian superoperator that governs the time evolution of the \n
system's density matrix. We find that the asymptotic decay rate to the \n
steady state generically remains nonzero in the thermodynamic limit\, i.e.\, \n
the spectrum of the superoperator is gaped as N approaches infinity. However\, \n
the size of the gap depends nontrivially on the strength of the coupling to \n
the environment. Initially\, the gap increases with the dissipation strength \n
but then reaches a maximum and declines upon additional strengthening of the \n
coupling. Furthermore\, a sharp spectral transition takes place: for \n
dissipation beyond a critical value\, the slowest decaying eigenvalues of the \n
Liouvillian separate from the main cloud of eigenvalues and become isolated \n
"midgap" states. I will discuss some of the implications of these findings.\n
\n
\n
link to recoreded talk [1]\n
\n
\n
[1] https://biu365-my.sharepoint.com/:v:/g/personal/ruhmanj_biu_ac_il/EUVv3iePXwFGqkx_69bAmWkBo6wMiz1_7XrFGu-Auzrp3A?e=30cyCu
END:VEVENT
BEGIN:VEVENT
UID:calendar:4807:field_when:0:4
SUMMARY:TBA
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200430T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200430T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4807
LOCATION:TBA
DESCRIPTION:Speaker: Elad Koren\n
\n
Abstract:\n
TBA
END:VEVENT
BEGIN:VEVENT
UID:calendar:4795:field_when:0:5
SUMMARY:Ising superconductors: the interplay of magnetic field\, triplet channels and \n
disorder
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200326T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200326T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4795
LOCATION:Zoom talk
DESCRIPTION:Speaker: David Mockli\n
\n
Abstract:\n
n the seminar\, I will give an introduction to unconventional 2D Ising \n
superconductors. Two examples are: lead on a silicon substrate and monolayer \n
transition metal dichalcogenides. I will detail the peculiar properties of \n
the superconducting state that emerges in the presence of Ising spin-orbit \n
coupling and an in-plane magnetic field. Orbital physics\, singlet-triplet \n
mixed Cooper pairs\, and the effect of impurities will be presented. \n
\n
\n
\n
Link to the seminar video [1]\n
\n
\n
[1] https://biu365-my.sharepoint.com/:v:/g/personal/ruhmanj_biu_ac_il/Ebs81N_QKpBGi5Wu4RaAIr0BMAnD1glVDHyA3wd9Tjwx3A?e=93MKyJ
END:VEVENT
BEGIN:VEVENT
UID:calendar:4793:field_when:0:6
SUMMARY:The Internal Structure of Vortices in Bosonic Superfluids and its \n
Implications
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200312T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200312T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4793
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Oded Agam\n
\n
Abstract:\n
The standard theory of bosonic superfluids assumes that vortices are \n
analogous to monopole point charges\, and are therefore characterized by \n
quantum numbers that describe only their position and (vorticity) charge. \n
This textbook description is derived from a cornerstone of fluid mechanics -- \n
the Kelvin theorem -- which invokes the conservation of circulation in the \n
dynamics of ideal incompressible fluids. However\, in this talk I will show \n
that in a broad class of superfluids\, vortices are characterized by an \n
additional degree of freedom\, affecting significantly various physical \n
phenomena. This new degree of freedom\, which endows to vortices a dipole-like \n
nature\, stems from a non-analytic "core reconstruction" which takes place in \n
superfluids with a large healing length\, yielding a set of excited states of \n
the vortex state with low energies and long lifetime. From a mathematical \n
perspective\, these new solutions of the Gross-Pitaevskii equations are \n
“weak solutions”. Namely\, they minimize the action but do not satisfy the \n
corresponding variational equations over a set of zero measure. The \n
consequences of the non-analytic core reconstruction regarding the transport \n
properties of velocities in disorder media and the instability of \n
Abrikosov’s lattice will be presented.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4747:field_when:0:7
SUMMARY:Lattice dynamics\, phonons and mechanics in disordered and dissipative systems
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200205T120000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200205T130000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4747
LOCATION:Resnick building (#202)\, 2nd floor\, seminar room
DESCRIPTION:Speaker: Alessio Zaccone (University of Milan / University of Cambridge)\n
\n
Abstract:\n
A new atomistic calculation methodology has been recently\n
developed which extends lattice dynamics to disordered and "real" solids\,\n
called Nonaffine Lattice Dynamics (NALD)\, based on the concept of nonaffine\n
displacements [1]\, which are ubiquitous in all real materials (crystals\n
with defects and grain boundaries\, glasses etc) and are deeply connected to\n
local topology of the lattice in terms of the statistical degree of local\n
centrosymmetry [2\,3]. This framework also allows one to predict the\n
dynamical mechanical response of "real" materials from the underlying\n
vibrational spectrum (VDOS) across the entire time-scale spectrum\, thus\n
providing a possible solution for the well known problem of bridging time\n
and length scales in the dynamical simulation of materials at the atomic\n
level. The method has been shown to be predictive on the example of a model\n
glassy material of Kremer-Grest polymer chains [4]\, and recent results\n
extend the description at the atomistic level for real polymer glasses\n
(polyethylene\, pDCPD\, pNBOH\, etc) [5]. I will also present recent results\n
aiming at rationalizing the effect of disorder and anharmonicity on phonons\n
in solids [6\,7]\, with implications for superconductivity in amorphous\n
materials [8].\n
\n
[1] A. Zaccone and E. Scossa-Romano\, Phys. Rev. B 83\, 184205 (2011).\n
[2] R. Milkus and A. Zaccone\, Phys. Rev. B 93\, 094204 (2016).\n
[3] B. Cui\, A. Zaccone\, D. Rodney\, J. Chem. Phys. 151\, 224509 (2019)\n
[4] V.V. Palyulin\, C. Ness\, R. Milkus\, R. Elder\, T. W. Sirk\, and A.\n
Zaccone\, Soft Matter 14\, 8475-8482 (2018).\n
[5] R. M. Elder\, A. Zaccone\, T. W. Sirk\, ACS Macro Letters 8\, 1160 (2019).\n
[6] M. Baggioli and A. Zaccone\, Phys. Rev. Lett. 122\, 145501 (2019).\n
[7] M. Baggioli and A. Zaccone\, arXiv:1911.03351 (2019).\n
[8] M. Baggioli\, C. Setty\, A. Zaccone\, arXiv:2001.00404 (2020).
END:VEVENT
BEGIN:VEVENT
UID:calendar:4744:field_when:0:8
SUMMARY:Cascade of Phase Transitions and Dirac Revivals in Magic Angle Graphene
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200123T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200124T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4744
LOCATION:Resnick conference room - building 209 2nd floor
DESCRIPTION:Speaker: Shahal Ilani\n
\n
Abstract:\n
Twisted bilayer graphene near the magic angle exhibits remarkably rich \n
electron correlation physics\, displaying insulating\, magnetic\, and \n
superconducting phases. Here\, using measurements of the local electronic \n
compressibility\, we reveal that these phases originate from a high-energy \n
state with an unusual sequence of band populations. As carriers are added to \n
the system\, rather than filling all the four spin and valley flavors equally\, \n
we find that the population occurs through a sequence of sharp phase \n
transitions\, which appear as strong asymmetric jumps of the electronic \n
compressibility near integer fillings of the moiré lattice. At each \n
transition\, a single spin/valley flavor takes all the carriers from its \n
partially filled peers\, "resetting" them back to the vicinity of the charge \n
neutrality point. As a result\, the Dirac-like character observed near the \n
charge neutrality reappears after each integer filling. Measurement of the \n
in-plane magnetic field dependence of the chemical potential near filling \n
factor one reveals a large spontaneous magnetization\, further substantiating \n
this picture of a cascade of symmetry breakings. The sequence of phase \n
transitions and Dirac revivals is observed at temperatures well above the \n
onset of the superconducting and correlated insulating states. This indicates \n
that the state we reveal here\, with its strongly broken electronic flavor \n
symmetry and revived Dirac-like electronic character\, is a key player in the \n
physics of magic angle graphene\, forming the parent state out of which the \n
more fragile superconducting and correlated insulating ground states emerge.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4733:field_when:0:9
SUMMARY:Combining thin films growth and spectroscopy for understanding the complex \n
oxide materials
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200116T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200116T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4733
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Muntaser Naamneh\n
\n
Abstract:\n
see attached file
END:VEVENT
BEGIN:VEVENT
UID:calendar:4714:field_when:0:10
SUMMARY:Scanning SQUID investigation of SrTiO3 domain walls
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200109T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200109T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4714
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Yiftach Frenkel\n
\n
Abstract:\n
The interface between the oxide insulators LaAlO3 and SrTiO3 hosts a gate \n
tunable 2D electron gas that also becomes SC at low temperatures. It has been \n
demonstrated that the 2DEG can be confined to create devices such as gate \n
defined SQUIDs or a single electron transistor.\n
\n
In effect the Physics of the SrTiO3 substrate play a major role in the \n
behavior of the interface. SrTiO3 undergoes a structural phase transition at \n
105K resulting in a dense network of domains separated by nano-meter thick \n
twin walls.\n
\n
I will discuss our recent findings\, where we used scanning SQUID microscopy \n
to map the spatial distribution of conduction at the interface. Images of the \n
interface showed channels of modulated current flow\, superconductivity and \n
magnetic signal. The domain walls change their location with thermal cycles \n
and with the application of back gate voltage. In addition we observed that \n
the domain wall behavior changes with application of stress. These findings \n
open exciting possibilities for normal and superconducting devices based on \n
domain walls
END:VEVENT
BEGIN:VEVENT
UID:calendar:4713:field_when:0:11
SUMMARY:Study of TLSs and mitigation of their deleterious effects in superconducting \n
circuits
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200102T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200102T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4713
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Moshe Schechter\n
\n
Abstract:\n
The generic existence of structural tunneling two-level systems (TLSs) in \n
amorphous solids was postulated by the "Standard Tunneling Model" to explain \n
the remarkable low temperature universality known by now to exist across the \n
different classes of disordered solids. Being ubiquitous at low energies\, \n
TLSs dominate low energy noise\, and as such restrict performance of quantum \n
nanodvices including superconducting qubits\, nanomechanical oscillators and \n
photon detectors. Recently\, the coupling of TLSs to superconducting qubits \n
and microresonators has facilitated novel experimental studies of TLSs\, \n
including detailed studies of individual TLSs and studies of the TLS glass \n
out of equilibrium. In this talk I will discuss some of these recent \n
experiments\, what insights they give with regard to the nature and \n
characteristics of TLSs\, and with regard to possibilities to mitigate the \n
deleterious effects of TLSs in microresonators and qubits.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4702:field_when:0:12
SUMMARY:Pseudo-Fields in Weyl materials
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191226T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191226T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4702
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Roni Ilan\n
\n
Abstract:\n
Topological Dirac and Weyl semimetals have an energy spectrum that hosts Weyl \n
nodes appearing in pairs of opposite chirality. We will discuss the effects \n
of inhomogeneities such as lattice deformations or a non-uniform \n
magnetization on the response and the energy spectrum of such materials. \n
These can arise either naturally or by engineering and can result\, for \n
example\, in a space-dependent Weyl node separation which can be interpreted \n
as an emergent axial vector potential. Consequently\, emerging pseudo fields \n
can derive equilibrium bound currents proportional to their strength that \n
average to zero over the sample\, and the interplay of pseudo fields and \n
external fields and can redistribute charge or chiral charge in real as well \n
as in momentum space via mechanisms such as the chiral anomaly. In addition\, \n
we will discuss how the topological surface states of Weyl semimetals\, the \n
Fermi arcs\, can be re-interpreted as an n=0 pseudo-Landau level resulting \n
from a pseudo-magnetic field confined to the surface\, and how a bulk \n
pseudo-magnetic field creates pseudo-Landau levels interpolating in real \n
space between Fermi arcs at opposite surfaces. Hallmarks of pseudo-fields can \n
appear in transport\, and we discuss ways to detect and quantify them and \n
contrast these with effects arising from external fields. Finally\, we will \n
discuss the manifestations of these ideas in metamaterials.\n
\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4696:field_when:0:13
SUMMARY:Synthetic dimensions: from topological energy pumping to Majorana \n
multiplexing
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191215T140000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191215T140000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4696
LOCATION:Resnick conference room - building 209 2nd floor
DESCRIPTION:Speaker: Gil Refael\n
\n
Abstract:\n
Periodic driving of quantum systems introduces new dimensions for controlling \n
quantum states. In my talk I will show how a time-periodic drive could be \n
considered as adding a dimension\, and how simple driven systems could acquire \n
topological features of higher-dimensional systems. Also\, I will discuss how \n
using several drives in parallel could produce new types of topological \n
states supporting multiple Majorana modes.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4695:field_when:0:14
SUMMARY:Hall conductivity as topological invariant in phase space
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191219T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191219T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4695
LOCATION:Resnick conference room - building 209 2nd floor
DESCRIPTION:Speaker: Ignat Fialkovskiy\n
\n
Abstract:\n
It is well known that quantum Hall conductivity in the presence of a constant \n
magnetic field is expressed through the topological TKNN invariant. The same \n
invariant is responsible for the intrinsic anomalous quantum Hall effect. We \n
propose a generalization of these expressions to the QHE in the presence of \n
non-uniform external fields. Our approach is based on purposely developed \n
lattice Wigner-Weyl formalism\, giving the Hall conductivity in terms of Weyl \n
symbols of the two-point Green's function. It is shown to be topological \n
invariant in the phase space of the system.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4663:field_when:0:15
SUMMARY:Valence-bond and gapless liquid states in triangular lattice SU(4) \n
antiferromagnets
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191205T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191205T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4663
LOCATION:Resnick conference room - building 209 2nd floor
DESCRIPTION:Speaker: Anna Keselman - UCSB\n
\n
Abstract:\n
In systems with many local degrees of freedom\, high-symmetry points in the \n
phase diagram can provide an important starting point for the investigation \n
of the broader phase diagram. In systems with both spin and orbital (or \n
valley) degrees of freedom\, SU(4)-symmetric models can serve as such a \n
starting point.\n
\n
In this talk I will discuss SU(4) quantum antiferromagnets on the triangular \n
lattice\, that arise from Mott-insulating phases of fermions with four \n
flavors. I will consider different fillings of the SU(4) fermions\, which lead \n
to different representations of SU(4) on each site.\n
\n
First\, I will discuss the case of two fermions per site (i.e. half-filling)\, \n
which corresponds to the 6-dimensional representation of SU(4). I will argue \n
that in this case\, the low energy properties of the model can be captured by \n
an effective dimer model. I will then present exact diagonalization studies \n
of the dimer model indicating that the ground state breaks translation \n
invariance\, forming a valence bond solid (VBS) with a 12-site unit cell.\n
\n
In the second part of my talk\, I will turn to the case of a single fermion \n
per site\, corresponding to the fundamental representation of SU(4). Based on \n
numerical simulations using the density matrix renormalization group (DMRG) \n
method\, supported by field-theoretical arguments\, I will provide evidence for \n
a gapless liquid with an emergent Fermi surface in the ground state of the \n
system.\n
\n
I will conclude with a discussion of SU(4)-symmetry breaking perturbations in \n
both cases.\n
\n
_________________________________________\n
\n
If you would like to book a meeting with Anna click here [1]\n
\n
\n
[1] https://doodle.com/poll/4q2tc2b6a9yt9cfx
END:VEVENT
BEGIN:VEVENT
UID:calendar:4669:field_when:0:16
SUMMARY:Crystalline symmetry in topological materials
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191128T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191128T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4669
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Raquel Queiroz\n
\n
Abstract:\n
Mathematics\, Physics and Chemistry meet most harmonically \n
through symmetry. Since Noether’s groundbreaking theorem\, which \n
established the connection between symmetry and a physical property\, \n
physicists have relied on symmetry arguments to understand the natural laws. \n
On the other hand\, the role of topology has been to some extent \n
under-appreciated and linked to specific exotic phenomena. However\, the two \n
are not far apart: topology regards constants of motion of the space of \n
states as a whole\, reflected in nonlocal (as opposed to local) properties of \n
physical systems\, and it is reflected by anomalous behavior at spatial \n
defects such as boundaries or vortices. In particular topology in band \n
structure theory remained elusive for the largest portion of its history. \n
Only the last decade has witnessed an enormous effort to bridge this gap\, \n
with remarkable success in the prediction of new physical phenomena. In this \n
talk\, I will focus on the interplay between topology and crystal symmetry in \n
band structure theory. I will show how spatial (unitary) symmetries which \n
were once expected to lead to trivial extensions of already known topological \n
phenomena\, can\, in fact\, introduce complexities that often defy our intuition \n
but at the same time can be used to make topological phenomena more \n
accessible to technological devices. I will show examples of how crystalline \n
topological phases may cease to exist with periodic boundaries\; how \n
crystalline symmetry (and its breaking) may lead to the confinement of \n
topological bands on crystalline defects such as stacking faults\; and \n
explored how the local symmetric environment may be manipulated through \n
intrinsic mechanisms to construct surface-based topological devices such as a \n
Majorana interferometer to probe non-abelian statistics.\n
\n
\n
\n
If you want to meet with Raquel please participate in the poll [1]\n
\n
\n
[1] https://doodle.com/poll/w4e6rq8rfaq4m7bt
END:VEVENT
BEGIN:VEVENT
UID:calendar:4564:field_when:0:17
SUMMARY:What is "strange" about non-Fermi liquid metals?
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190707T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190707T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4564
LOCATION:TBA
DESCRIPTION:Speaker: Debanjan Chowdhury - Cornell\n
\n
Abstract:\n
The concept of electronic quasiparticles\, as introduced by Landau\, is one of \n
the cornerstones of the theory of quantum many-body systems. However\, a \n
growing number of recent experiments in strongly correlated quantum \n
materials have forced us to confront the existence of quantum matter for \n
which the concept of electronic quasiparticles does not apply. Inspired by \n
the rich phenomenology of the parent states of numerous high-temperature \n
superconductors\, I will describe some recent progress in our understanding of \n
metallic states that do not admit a quasiparticle description but that \n
nonetheless have a sharply-defined Fermi surface. I will present some \n
experimental results on unconventional transport properties \n
of magic-angle twisted bilayer graphene and comment on their possible \n
connections with the rest of my talk.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4585:field_when:0:18
SUMMARY:Pascal conductance series in ballistic one-dimensional LaAlO3/SrTiO3 channels
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190801T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190801T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4585
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Jeremy Levy - Pitt\n
\n
Abstract:\n
tba
END:VEVENT
BEGIN:VEVENT
UID:calendar:4625:field_when:0:19
SUMMARY:Vestigial orders in electronic correlated systems: nematicity and beyond
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190919T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190919T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4625
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Rafael Fernandes - Minnesota University\n
\n
Abstract:\n
A hallmark of the phase diagrams of correlated electronic systems is the \n
existence of multiple electronic ordered states. In many cases\, they cannot \n
be simply described as independent competing phases\, but instead display a \n
complex intertwinement. A prime example of intertwined states is the case of \n
primary and vestigial phases. While the former is characterized by a \n
multi-component order parameter\, the fluctuation-driven vestigial state is \n
characterized by a composite order parameter formed by higher-order\, \n
symmetry-breaking combinations of the primary order parameter. This concept \n
has been widely employed to elucidate nematicity in both iron-based and \n
cuprate superconductors. In this talk\, I will present a group-theoretical \n
framework\, supplemented by microscopic calculations\, that extends this notion \n
to a variety of phases\, providing a general classification of vestigial \n
orders of unconventional superconductors and density-waves. Electronic states \n
with scalar and vector chiral order\, spin-nematic order\, Ising-nematic order\, \n
time-reversal symmetry-breaking order\, and algebraic vestigial order emerge \n
from this simple underlying principle. I will present a rich variety of \n
possible phase diagrams involving the primary and vestigial orders\, and \n
discuss possible realizations of these exotic composite orders in different \n
materials.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4657:field_when:0:20
SUMMARY:Transport and pumping from Majorana manipulations
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191114T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191114T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4657
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Dganit Median - BGU\n
\n
Abstract:\n
Majorana zero modes are non-Abelian quasiparticles that emerge on the edges \n
of topological phases of superconductors. Evidence of their presence have \n
been reported in transport measurements on engineered superconducting-based \n
nanostructures. In this talk I will discuss transport signatures of dynamical \n
Majorana manipulation. In the first part of the talk I will show that \n
adiabatic exchange of a pair of Majorana zero modes leads to quantized heat \n
pumping. This feature is inherent to the presence of Majorana zero modes and \n
I will discuss its robustness against temperature\, voltage bias and the \n
detailed coupling to the contacts. Next I will discuss \n
conductance measurements of a Floquet Majorana wire. For this purpose I will \n
relate the scattering matrix of the time dependent system to a fictitious \n
stroboscopic scattering matrix. Using this simplified scattering problem I \n
will calculate the conductance in the 4 topologically distinct phases that \n
occur in the Floquet Kitaev wire.\n
\n
\n
\n
To book a meeting with Dganit click here [1]\n
\n
\n
[1] https://doodle.com/poll/5da6fea2gddmitwu
END:VEVENT
BEGIN:VEVENT
UID:calendar:4661:field_when:0:21
SUMMARY:Fragility of the dissipationless state in a clean two-dimensional \n
superconductor 2H-NbSe2
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191212T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191212T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4661
LOCATION:Resnick conference room - building 209 2nd floor
DESCRIPTION:Speaker: Avishai Benyamini\n
\n
Abstract:\n
In my talk\, I will tell about my interest in emergent phenomena and how the \n
extreme tunability of 2D materials is an unprecedented tool-box to \n
investigate emergent and novel physical phenomena. I will discuss the \n
importance of scanning probes and my plan to establish a new scanning \n
platform based on 2D materials. I will then talk about my work in Columbia on \n
an air-sensitive van der Waals superconductor 2H-NbSe2. How we established a \n
new technique to contact and preserve the material. That we resolved a \n
20-year-old open question regarding the nature of an anomalous metallic state \n
in the superconducting dome of thin-film superconductors (in collaboration \n
with Danny Shahar\, Weizmann). We found that in both 2H-NbSe2 and amorphous \n
InOx\, the anomalous metallic state was a non-equilibrium steady-state driven \n
by electronic noise. With no added noise\, I will present measurements of the \n
dissipation phase diagrams of superconductivity in the two dimensional (2D) \n
limit\, layer by layer\, down to a monolayer in the presence of temperature \n
(T)\, magnetic field (B)\, and current (I) in 2H-NbSe2. Our results show that \n
the phase-diagram strongly depends on the thickness\, even in the 2D limit. At \n
four layers we can define a finite region in the I-B phase diagram where \n
dissipationless transport exists at T=0. At even smaller thicknesses\, this \n
region shrinks in area until\, in a monolayer\, it approaches a single point \n
defined by I=B=T=0. In applied field\, we show that \n
time-dependent-Ginzburg-Landau (TDGL) simulations that describe dissipation \n
by vortex motion\, qualitatively reproduce our experimental I-B phase diagram. \n
We show that by using non-local transport and TDGL calculations that we can \n
engineer charge flow and create phase boundaries between dissipative and \n
dissipationless transport regions in a single sample\, demonstrating control \n
over non-equilibrium states of matter.\n
\n
\n
\n
If time permits\, I will show new results which we understand as a blockade of \n
vortex transport due to thermal fluctuations.\n
\n
\n
\n
\n
\n
[1] Nano Letters 2018\n
\n
[2] Science Advances 2019\n
\n
[3] Nature Physics 2019\n
\n
[4] In review PRL\, arXiv:1909.08469
END:VEVENT
BEGIN:VEVENT
UID:calendar:4658:field_when:0:22
SUMMARY:Variational-Correlations Approach to Quantum Many-Body Physics
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191121T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191121T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4658
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Arbel Haim\n
\n
Abstract:\n
I will present a variational method for studying the ground state of a \n
quantum many-body Hamiltonian\, which treats the correlation functions as \n
variational parameters. This numerical approach is based on approximating the \n
positivity of the density matrix in a controlled manner\, and allows for \n
obtaining the (approximate) ground state in polynomial time. Unlike the \n
conventional variational principle which provides an upper bound on the \n
ground-state energy\, in this approach one obtains a lower bound on the \n
ground-state energy. I will demonstrate the method on several one-dimensional \n
spin 1/2 Hamiltonians. Possible extensions of the method will be discussed.\n
\n
\n
\n
To book a meeting with Arbel click here [1]\n
\n
\n
[1] https://doodle.com/poll/s7fhr6r8cyap6zue
END:VEVENT
BEGIN:VEVENT
UID:calendar:4635:field_when:0:23
SUMMARY:Topological protection of Weyl fermions tested on the atomic scale
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191031T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191031T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4635
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Haim Beidenkopf - Weizmann institute\n
\n
Abstract:\n
Topological electronic materials host exotic boundary modes\, that cannot be \n
realized as standalone states\, but only at the boundaries of a topologically \n
classified bulk. Topological Weyl semimetals\, whose bulk electrons exhibit \n
chiral Weyl-like dispersion\, host Fermi-arc states on their surfaces. The \n
Fermi-arc surface bands disperse along open momentum contours terminating at \n
the surface projections of bulk Weyl nodes with opposite chirality. Such \n
reduction of the surface degrees of freedom by their splitting and \n
segregation to opposite surfaces of the sample\, that reoccurs in all \n
topological states of matter and even exhibited by topological defects [1]\, \n
provides topological protection from their surface elimination. We have \n
confirmed the Weyl topological classification of both the inversion symmetry \n
broken compound TaAs [2] and the time reversal symmetry broken Co3Sn2S2 [3] \n
by spectroscopic visualization of their Fermi-arc surface states through the \n
interference patterns those electrons embed in the local density of states. \n
This has allowed us to examine their unique nature and level of protection \n
against perturbations. In TaAs the Fermi arc bands are found to be much less \n
affected by the surface potential compared to trivial bands that also exist \n
on its surfaces. In contrast\, in Co3Sn2S2 the dispersion of the topological \n
Fermi-arc bands\, and even their inter-Weyl node connectivity\, are found to \n
vary with the surface termination. This discrepancy seems to elude towards a \n
tradeoff between momentum extended Fermi-arc bands\, as those in Co3Sn2S2\, \n
which have more pronounced experimental signatures but are more susceptible \n
to surface perturbations\, to short extent ones\, as those in TaAs\, which are \n
harder to detect but are more robust.\n
\n
\n
\n
[1] Abhay Kumar Nayak et al\, “Resolving the Topological \n
Classification of Bismuth with Topological Defects” Science Advances (in \n
press)\; arXiv:1903.00880\n
\n
[2] Rajib Batabyal et al\, “Visualizing weakly bound surface \n
Fermi arcs and their correspondence to bulk Weyl fermions” Science \n
Advances 2\, e1600709 (2016)\n
\n
[3] Noam Morali et al\, “Fermi-arc diversity on surface \n
terminations of the magnetic Weyl semimetal Co3Sn2S2” Science 365\, 1286 \n
(2019)\n
\n
\n
\n
To scheduele a meeting reserve a slot here [1]\n
\n
\n
[1] https://doodle.com/poll/cupkm6mnsnii66vh
END:VEVENT
BEGIN:VEVENT
UID:calendar:4636:field_when:0:24
SUMMARY:Nanoscale imaging of quantum Hall edge currents in single layer graphene and \n
in magic angle twisted bilayer graphene
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191107T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20191107T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4636
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Aviram Uri - Weizmann institute\n
\n
Abstract:\n
See attached file for abstract
END:VEVENT
BEGIN:VEVENT
UID:calendar:4556:field_when:0:25
SUMMARY:Hall effect in strongly corelated metals
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190619T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190619T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4556
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Assa Aurbach\n
\n
Abstract:\n
An exact formula for the temperature dependent Hall number of metals is \n
derived. It is valid for nonrelativistic fermions or bosons\, with an \n
arbitrary potential and interaction. This dc transport coefficient is proven \n
to (remarkably) depend solely on equilibrium susceptibilities\, which are more \n
amenable to numerical algorithms than the conductivity. An application to \n
strongly correlated phases is demonstrated by calculating the Hall sign in \n
the vicinity of Mott phases of lattice bosons.\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4559:field_when:0:26
SUMMARY:Graphene at Very High Magnetic Fields
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190605T121500
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190605T121500
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4559
LOCATION:Resnick seminar room - 2nd floor
DESCRIPTION:Speaker: Ganpathy Murthy\, University of Kentucky\n
\n
Abstract:\n
In the Hofstadter problem\, an orbital flux of the order of a flux quantum \n
goes through each unit cell. There are some special features when one \n
considers a honeycomb lattice. For a certain class of hopping problems \n
obeying a nonunitary "chiral " symmetry\, when 1/q quanta of flux penetrate \n
each unit cell\, the central two bands touch at 2q Dirac points. These \n
touchings are protected by lattice symmetries and the "chiral" symmetry. When \n
simple short-range interactions are introduced\, we find a plethora of phases \n
which have charge\, magnetic\, and/or bond order. I will compare this to \n
Kharitonov's phase diagram in the continuum limit for tiny fields.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4555:field_when:0:27
SUMMARY:Nonlocal adiabatic response of Disordered-Insulators
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190613T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190613T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4555
LOCATION:Resnick conference room - Resnick building 2nd floor
DESCRIPTION:Speaker: Zvi Ovadyahu\n
\n
Abstract:\n
Charge transport in Anderson insulators is governed by disorder and Coulomb \n
interactions and their competition leads to glassy behavior. This has been \n
experimentally observed in heavily-doped semiconductors where the disorder \n
necessary to render them Anderson-insulators is large enough to reduce \n
electronic relaxation rates many decades below inter-sites transition-times \n
associated with their conductivity.\n
In this talk\, use will be made of this characteristic feature to \n
demonstrate another inherent feature of disordered insulators\; a \n
time-dependent local perturbation may induce a nonlocal response over scales \n
that may extend much further than the localization length.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4533:field_when:0:28
SUMMARY:Robust high resolution MRI by spatiotemporal encoding
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190530T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190530T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4533
LOCATION:Building 202 room 303
DESCRIPTION:Speaker: Lucio Frydman\n
\n
Abstract:\n
Over the last decade we have introduced and perfected so-called \n
spatiotemporal encoding (SPEN) methodologies to collect multidimensional NMR \n
spectra and images in a single scan. This talk will focus on the new spin \n
physics underlying these methodologies\, and on the potential of these \n
techniques to deliver superior imaging information\, particularly in \n
comparison with established methods such as spin-echo EPI in the realm of \n
diffusion MRI\, and with fast-spin-echo/RARE in multi-shot anatomical MRI. \n
Achievements that will be described include the acquisition of diffusion in \n
vivo images at <100µm in-plane resolutions in challenging preclinical areas\, \n
hitherto unavailable characterizations of cancerous tissues in animals and in \n
patients\, and sub-mm anatomical measurements in humans with unprecedented \n
acceleration factors.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4532:field_when:0:29
SUMMARY:Topology by dissipation: Novel transport properties and disorder-induced \n
criticality
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190523T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190523T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4532
LOCATION:Resnick seminar room - 2nd floor
DESCRIPTION:Speaker: Moshe Goldstein\n
\n
Abstract:\n
Nonequilibrium conditions are traditionally seen as detrimental to the \n
appearance of quantum coherent many-body phenomena in condensed matter \n
systems\, and much effort is often devoted to their elimination. Recently this \n
approach has changed: It has been realized that driven-dissipative Markovian \n
dynamics of the Lindblad type could be used as a resource. By proper \n
engineering of the reservoirs and their local couplings to a system\, one may \n
drive the system towards desired quantum-correlated steady states\, even in \n
the absence of internal Hamiltonian dynamics.\n
\n
An intriguing category of nontrivial equilibrium many-particle phases are \n
those which are distinguished by topology rather than by symmetry. Natural \n
questions thus arise: Which of these topological states can be achieved as \n
the result of purely dissipative Lindblad-type dynamics? Could they display \n
novel behavior\, with no equilibrium analogues? Besides the fundamental \n
importance of these issues\, they may offer novel routes to the realization of \n
topologically-nontrivial states in quantum simulators\, especially ultracold \n
atomic gases.\n
\n
In our previous work we have provided a no-go theorem determining which \n
Gaussian (noninteracting) topological states are achievable as the unique \n
steady states of local dissipative dynamics\, as well as a general recipe for \n
creating\, identifying and classifying the achievable states in ultracold \n
atoms and related systems. After reviewing this work I will discuss two newer \n
developments:\n
\n
1. What are the resulting transport properties\, such as persistent currents \n
and conductivity? We find that\, in contrast with equilibrium systems\, the \n
usual relation between the Chern topological number and the Hall conductivity \n
is broken. We explore the intriguing edge dynamics and elucidate under which \n
conditions the Hall conductivity is quantized.\n
\n
2. We show that dissipation-induced topology is robust against weak disorder\, \n
but may break down under strong enough disorder\, with a critical point \n
separating the two regimes. Surprisingly\, disordered dissipation leads to a \n
critical point similar to the equilibrium one\, while disordered Hamiltonian \n
in the presence of dissipation leads to a novel critical point with \n
significantly different critical exponents.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4528:field_when:0:30
SUMMARY:Hot superconductors and cold insulators
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190516T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190516T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4528
LOCATION:Building 202 room 303
DESCRIPTION:Speaker: Dan Shahar\n
\n
Abstract:\n
The study of the magnetic-field driven superconductor-insulator transition in \n
thin superconducting films at low temperatures reveals an unusual insulator \n
whose conductivity seems to approach zero at a finite temperature\, while its \n
current-voltage characteristics are bistable\, indicating that the electrons \n
decouple from the phonon system\, In parallel\, the superconducting state at \n
lower magnetic fields exhibits a broad range where metallic behavior is seen \n
down to the lowest temperatures.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4436:field_when:0:31
SUMMARY:Ordered Defects: A road map towards room temperature Superconductivity and \n
Magnetic Order
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190606T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190606T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4436
LOCATION:TBD
DESCRIPTION:Speaker: Pablo Esquinazi (Leipzig)\n
\n
Abstract:\n
Defects in the atomic lattice of solids are sometimes desired. For example\, \n
atomic vacancies\, single ones or more elaborated defective structures\, can \n
generate localized magnetic moments in a non-magnetic crystalline lattice. \n
Increasing their density to a few percent magnetic order can appear. \n
Furthermore\, usual graphite samples\, independently whether they are from \n
natural sources\, Kish or highly oriented pyrolytic graphite\, bulk or powder \n
samples\, have interfaces. These interfaces occur between twisted regions with \n
Bernal or rhombohedral or between Bernal and rhombohedral stacking orders. I \n
discuss old and new results - from single interfaces (bilayer graphene) to \n
multigraphene and bulk or powder graphite samples - that speak for the \n
existence of superconductivity with a broad distribution of critical \n
temperatures. Especial emphasis will be given to new results\, which indicate \n
the existence of granular superconductivity even above room temperature.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4496:field_when:0:32
SUMMARY:Competing orders in non-centrosymmetric superconductors
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190404T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190404T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4496
LOCATION:Reznik Building 209 room 210
DESCRIPTION:Speaker: Maxim Khodas\n
\n
Abstract:\n
As a motivation I review several recent experiments on transition metal \n
dichalcogenides.\n
\n
Then I will present what is known about these materials and what makes there \n
response to the magnetic field special. \n
\n
I will then review the spin-orbit coupling based on symmetry \n
considerations.\n
\n
Then I'll focus on the singlet to triplet conversion induced by the Zeeman \n
field.\n
\n
Finally I'd discuss the effect this has on the critical field.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4495:field_when:0:33
SUMMARY:Tunneling spectroscopy in van-der-Waals superconducting devices
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190328T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190328T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4495
LOCATION:Nano building 9th floor
DESCRIPTION:Speaker: Hadar Steinberg - Racah Institute of Physics\, Hebrew University\, \n
Jerusalem\, Israel\n
\n
Abstract:\n
I will describe our experiments probing the tunneling spectra of the layered \n
superconductor NbSe2 using van-der-Waals tunnel junctions. The junctions\, \n
characterized by a hard gap\,enable the measurement of high resolution spectra \n
and the probing of sub-gap states. Usingthis method\, we make a number of key \n
findings: (i) We find a clear signature of a 2nd \, low-energy gap\, in \n
NbSe2 . By measuring the spectra vs. in-plane and out-of-plane fields\, we \n
can place values on its diffusion constant and coherence length. (ii) We \n
probe NbSe2 spectra at the ultrathin limit. We find that thin NbSe2 retains \n
its gap up well above the Pauli limit\, a consequence of Ising protection. \n
(iii) Finally\, we find that van-der-Waals tunnel barriers host defects which \n
undergo proximity with the underlying superconductor\, giving rise to Andreev \n
bound states. As NbSe2 survives very high in-plane fields\, we can track the \n
defect state energy which exhibits a field-dependent singlet-doublet \n
transition. I will discuss possible origins of the singlet-ground state \n
behavior of defect-related Andreev bound states.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4497:field_when:0:34
SUMMARY:Dynamics on the edge: charge fractionalization and non-equilibrium \n
bosonization
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190314T121500
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190314T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4497
LOCATION:Nano Building 9th floor
DESCRIPTION:Speaker: Bernd Rosenow\n
\n
Abstract:\n
In quantum Hall edge states\, charge fractionalization can occur due to \n
injection of charge pulses\, which decompose into eigenmodes propagating at \n
different velocities. The method of non-equilibrium bosonization allows to \n
distinguish the regimes of quasi-particle creation and local equilibration\, \n
and to characterize the final prethermalized state. Comparison with \n
experimental results gives good agreement and allows to determine the \n
velocities of edge modes.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4489:field_when:0:35
SUMMARY:Hot electron generation in plasmonic nanostructures – thermal vs. \n
non-thermal effects
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190307T121500
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190307T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4489
LOCATION:Nano Building 9th floor
DESCRIPTION:Speaker: Yonathan Sivan BGU\n
\n
Abstract:\n
We present a self-consistent theory of the steady-state electron distribution \n
in metals under continuous-wave illumination which treats\, for the first \n
time\, both thermal and non-thermal effects on the same footing. We show the \n
number of non-thermal electrons (i.e.\, the deviation from thermal \n
equilibrium) is a very small effect\, namely\, that the power that ends up \n
generating these non-thermal electrons is many orders of magnitude smaller \n
than the amount of power that leads to regular heating.\n
\n
Using this theory\, we re-examine the exciting claims on the possibility to \n
enhance chemical reactions with these non-thermal electrons. We identify a \n
series of errors in the temperature measurements in some of the most famous \n
paper on the topic which led their authors to under estimate regular heating \n
effects. As an alternative\, we show that a very simple theory\, based on just \n
simple heating\, can explain the published experimental data with excellent \n
accuracy.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4477:field_when:0:36
SUMMARY:Nonlinear light-matter interaction: from superconducting qubits to spins in \n
diamond
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190228T121500
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190228T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4477
LOCATION:Nano Building 9th floor
DESCRIPTION:Speaker: Eyal Buks\n
\n
Abstract:\n
Cavity quantum electrodynamics (CQED) is the study of the interaction between \n
matter and photons confined in a cavity. In the Jaynes-Cummings model the \n
matter is described using the two-level approximation\, and only a single \n
cavity mode is taken into account. The interaction has a relatively large \n
effect when the ratio /E//ℏω between the energy gap /E/ separating the two \n
levels and the cavity mode photon energy ℏω is tuned close to unity.\n
\n
The talk is devoted to the study of the light-matter interaction in the \n
nonlinear regime using three different CQED systems. In the first experiment \n
a Josephson flux qubit serves as a two-level system and a superconducting \n
resonator as the cavity [1]. We experimentally find that the cavity response \n
exhibits higher order resonances (called /super-harmonic/ resonances) in the \n
nonlinear regime when the ratio /E//ℏω is tuned close to an integer value \n
larger than unity. Moreover\, we observe is significant narrowing in the \n
cavity resonance that is induced by qubit driving\, and which is attributed to \n
quantum jumps. In the second experiment the interaction between a spin \n
ensemble of diphenylpicrylhydrazyl (DPPH) molecules and a superconducting \n
resonator is explored in the region where /E//ℏω≫1 [2]. We find that the \n
cavity response is significantly modified when the spins are intensively \n
driven close to their Larmor frequency. Retardation in the response of the \n
spin ensemble gives rise to effects such as cavity mode cooling and heating. \n
In the third experiment the interaction between nitrogen-vacancy (NV) and \n
nitrogen substitutional (P1) spin defects in diamond and a superconducting \n
resonator is studied [3]. We find that nonlinearity imposes a fundamental \n
limit upon sensitivity of CQED-based spin detection. Moreover\, multi-photon \n
resonances are observed when the ratio between the Larmor frequency and the \n
driving frequency is tuned close to an integer value and the CQED system is \n
tuned close to its resonance /E//ℏω=1. In addition\, other experimentally \n
observed multi-photon resonances are attributed to the dipolar coupling \n
between NV and P1 defects.\n
\n
*References*\n
\n
1. Eyal Buks\, Chunqing Deng\, Jean-Luc F.X. Orgazzi\, Martin Otto and Adrian \n
Lupascu\, Phys. Rev. A 94\, 033807 (2016).\n
\n
2. Hui Wang\, Sergei Masis\, Roei Levi\, Oleg Shtempluk and Eyal Buks\, Phys. \n
Rev. A 95\, 053853 (2017).\n
\n
3. Nir Alfasi\, Sergei Masis\, Roni Winik\, Demitry Farfurnik\, Oleg Shtempluck\, \n
Nir Bar-Gill and Eyal Buks\, Phys. Rev. A 97 (2018).
END:VEVENT
BEGIN:VEVENT
UID:calendar:4469:field_when:0:37
SUMMARY:?Can a machine infer quantum mechanics
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190221T121500
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190221T121500
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4469
LOCATION:Nano 9th floor
DESCRIPTION:Speaker: Shay Hacohen Gourgy\n
\n
Abstract:\n
At its core\, Quantum Mechanics is a theory developed to describe fundamental \n
observations in the spectroscopy of solids and gases. Despite these practical \n
roots\, however\, quantum theory is infamous for being highly counterintuitive\, \n
largely due to its intrinsically probabilistic nature. Neural networks have \n
recently emerged as a powerful tool that can extract non-trivial correlations \n
in vast datasets. They routinely outperform state-of-the-art techniques in \n
language translation\, medical diagnosis and image recognition. It remains to \n
be seen if neural networks can be trained to predict stochastic quantum \n
evolution without a priori specifying the rules of quantum theory. I will \n
show how we trained a recurrent neural network to infer the individual \n
quantum trajectories associated with the evolution of a superconducting qubit \n
under unitary evolution\, decoherence and continuous measurement from raw \n
observations only. The network extracts the system Hamiltonian\, measurement \n
operators and physical parameters. It is also able to perform tomography of \n
an unknown initial state without any prior calibration. This method has \n
potential to greatly simplify and enhance tasks in quantum systems such as \n
noise characterization\, parameter estimation\, feedback and optimization of \n
quantum control. \n
\n
Arxiv:1811.12420
END:VEVENT
BEGIN:VEVENT
UID:calendar:4435:field_when:0:38
SUMMARY:Strong repulsive and attractive interactions in correlated dipolar quantum \n
fluids
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190110T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190110T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4435
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Ronen Rapaport (Weizmann)\n
\n
Abstract:\n
Quantum fluids of matter with long range\, anisotropic interactions display \n
rich emergent collective phenomena. A prominent example is the dipole-dipole \n
interaction\, which has recently been addressed by a growing community\, both \n
from atomic physics as well as from condensed matter physics\, with the latter \n
being focused on dipolar quantum fluids of two-dimensional excitons\, and very \n
recently\, on the introduction of interacting dipolar polaritons. These \n
strongly interacting dipolar exciton and polariton systems offer \n
opportunities to explore new collective phenomena which are currently \n
inaccessible with atomic dipolar gases\, and to demonstrate new types of \n
quantum devices on the level of two-particle interaction.\n
\n
In this talk I will present several recent results in systems of dipolar \n
excitons and polaritons. These include strong experimental evidence for the \n
dynamical formation of a robust dark quantum liquid phase of dipolar excitons \n
in a bilayer system. This observation is corroborated by a surprising theory \n
predicting a remarkable stabilization of a dense dark-spin exciton \n
Bose-Einstein condensate\, driven by particle correlations due to the strong \n
dipolar interactions. Also\, I will report on the first observation of a \n
formation of an attractive polaron-like many-body correlated state of \n
vertically coupled dipolar exciton fluids. Finally\, I will introduce recent \n
experiments showing formation of flying electrically polarized \n
dipolar-polaritons (dipolaritons) in optical waveguides\, resulting in a very \n
large\, electrically tunable enhancement of the polariton-polariton \n
interactions\, a result promising for future implementations of a dipolar \n
polariton blockade.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4362:field_when:0:39
SUMMARY:Robust high resolution MRI by spatiotemporal encoding
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190103T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190103T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4362
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Lucio Frydmann (Weizmann)\n
\n
Abstract:\n
Over the last decade we have introduced and perfected so-called \n
spatiotemporal encoding (SPEN) methodologies to collect multidimensional NMR \n
spectra and images in a single scan. This talk will focus on the new spin \n
physics underlying these methodologies\, and on the potential of these \n
techniques to deliver superior imaging information\, particularly in \n
comparison with established methods such as spin-echo EPI in the realm of \n
diffusion MRI\, and with fast-spin-echo/RARE in multi-shot anatomical MRI. \n
Achievements that will be described include the acquisition of diffusion in \n
vivo images at <100µm in-plane resolutions in challenging preclinical areas\, \n
hitherto unavailable characterizations of cancerous tissues in animals and in \n
patients\, and sub-mm anatomical measurements in humans with unprecedented \n
acceleration factors.\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4406:field_when:0:40
SUMMARY:Through the looking glass: optical spectroscopy of electronic correlations
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190101T120000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20190101T130000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4406
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Nimrod Bachar (Geneva)\n
\n
Abstract:\n
Many body systems involving strongly interacting electrons exhibit various \n
rich and interesting physical states\, such as Mott insulators\, \n
superconductors\, heavy Fermions and etc. Optical properties serve as an \n
important tool to study these correlations and their resulting collective \n
excitations. In my talk I will briefly review several examples of our \n
experimental observations regarding: I. Pairing symmetry\, energy gap\, \n
superfluid stiffness and phase collective modes in superconducting thin films \n
[1\,2\,3]. II. Hybridization of localized and conduction energy bands and their \n
optical plasmons in heavy Fermion systems [4]. III. The interplay between the \n
coherent and incoherent sectors of the dynamic conductivity of doped Mott \n
insulator systems [5]. I will then dwell into the latter example and show the \n
in-plane dynamic and static charge conductivity of electron doped Sr2IrO4 \n
using optical spectroscopy and DC transport measurements. I will demonstrate \n
the similarity of the optical signature for a pseudo-gap in several systems. \n
Based on these similarities\, and the absence of a correlation between \n
superconductivity and pseudo-gap in the doped iridate compound I will argue \n
that the pseudo-gap is a signature of the presence of residual correlations \n
inherited from the insulating anti-ferromagnetic state.\n
\n
1. U. S. Pracht\, N.B. et al.\, Phys. Rev. B 93\, 100503(R) (2016).\n
2. U. S. Pracht et al.\, Phys. Rev. B 96\, 094514 (2017).\n
3. N.B. et al.\, EPL (Europhysics Letters) 104\, 67006 (2013).\n
4. N.B. et al.\, Phys. Rev. B 94\, 235101 (2016).\n
5. K. Wang\, N.B. et al.\, Phys. Rev. B 98\, 045107 (2018).
END:VEVENT
BEGIN:VEVENT
UID:calendar:4361:field_when:0:41
SUMMARY:Theory of bistable correlated nonlinear oscillators in circuit quantum \n
electrodynamics
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181227T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181227T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4361
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Eran Ginossar (Surrey\, UK)\n
\n
Abstract:\n
We will describe our theoretical and experimental work towards understanding \n
the joint activated dynamics exhibited by two superconducting quantum \n
oscillators. The open quantum systems approach can describe a cavity mode \n
oscillator which is strongly coupled to a superconducting qubit in the \n
strongly coherently driven dispersive regime. We will start by introducing \n
previous work ranging from the quantum optical stochastic methods\, exact \n
solutions in phase space and methods of non-equilibrium field theory. Next we \n
will explain the challenge of extending the application of these methods to \n
two oscillators and to the non-semi-classical regime. We will survey our \n
early work on this problem which started by earlier theoretical work on the \n
use of strongly driving pulses for quantum state detection [1\,2\,3]. Recent \n
collaboration with experiments have encouraged us to apply a range of methods \n
and we uncovered some surprising dynamical behaviour of the including a joint \n
bistability of the generalised Jaynes-Cummings model [4\,5]\, meta-stable dark \n
states [6] and critical slowing down of the system [7] which are properties \n
of the bistability in two degrees of freedom.\n
\n
\n
\n
[1] E. Ginossar and Lev S Bishop and D. I Schuster and S. M Girvin\, Protocol \n
for high fidelity readout in the photon blockade regime of circuit QED\,Phys. \n
Rev. A 82\,022335 (2010)\n
\n
[2] Lev S. Bishop\, Eran Ginossar\, and S. M. Girvin\, Response of the Strongly \n
Driven Jaynes-Cummings Oscillator\, Phys. Rev. Lett. 10 \, 100505 (2010)\n
\n
[3] M. D. Reed\, L. DiCarlo\, B. R. Johnson\, L. Sun\, D. I. Schuster\, L. \n
Frunzio\, R. J. Schoelkopf\, High-Fidelity Readout in Circuit Quantum \n
Electrodynamics Using the Jaynes-Cummings Nonlinearity\, Phys. Rev. Lett. \n
173601 (2010)\n
\n
[4] Th. K. Mavrogordatos\, G. Tancredi\, M. Elliott\, M. J. Peterer\, A. \n
Patterson\, J. Rahamim\,2 P. J. Leek\, E. Ginossar\, and M. H. Szymanska\, \n
Simultaneous Bistability of a Qubit and Resonator in Circuit Quantum \n
Electrodynamics\, Phys. Rev. Lett. 040402 (2017)\n
\n
[5] Matthew Elliott and Eran Ginossar\, Applications of the Fokker-Planck \n
equation in circuit quantum electrodynamics\, Phys. Rev. A 94\, 043840 (2016)\n
\n
[6] Th. K. Mavrogordatos\, F. Barratt\, U. Asari\, P. Szafulski\, E. Ginossar\, \n
and M. H. Szymańska \,Rare quantum metastable states in the strongly \n
dispersive Jaynes-Cummings oscillator\, Phys. Rev. A 97\, 033828 (2018)\n
\n
[7] P. Brooks\, G. Tancredi et al.\, in preparation.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4410:field_when:0:42
SUMMARY:Universal features in disordered solids: Implications for directed aging and \n
the creation of non-linear metamaterials
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181220T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181220T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4410
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Daniel Hexner - UChicago\n
\n
Abstract:\n
The most obvious and distinctive feature of an amorphous solid is its \n
heterogeneous microscopic structure. A central issue is how such disorder \n
governs the elastic properties of an amorphous solid so that it has different \n
behavior from its crystalline counterpart. I will show how such disorder on \n
the microscale determines the elastic properties on long length scales. This \n
theoretical approach ultimately allows us to control a material’s elastic \n
properties and to understand how a material ages and stores memories. \n
\n
I start by studying the change in an amorphous solid’s elastic properties \n
upon the removal of a single bond. I show that the change in moduli\, which \n
has a broad and universal shape\, is uncorrelated for different imposed \n
strains.Thus\, by selectively removing a small number of bonds\, the precise \n
global and local elastic behavior of the solid can be controlled. This in \n
turn suggests that small changes in bond properties\, which occur naturally as \n
a solid ages\, can dramatically alter the solid’s elastic response\; the \n
history of imposed strains is encoded in the non-linear response and the \n
aging process\, usually considered to be detrimental\, can be harnessed to \n
design materials with novel desired properties.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4360:field_when:0:43
SUMMARY:The Gas Liquid Transition of Excitons: from Bose glass to BEC
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181213T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181213T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4360
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Israel Bar Joseph (Weizmann)\n
\n
Abstract:\n
In this talk I shall review our work on the gas-liquid transition of 2D \n
excitons in GaAs quantum wells. Below a critical temperature and above a \n
critical density this system undergoes a phase transition to a liquid state. \n
By employing a variety of optical spectroscopy tools we map the phase diagram \n
of the system\, and show that the liquid is a Bose Einstein condensate of dark \n
excitons (exciton state which is not coupled to light).\n
\n
We find that the liquid phase is fragmented below Tc and the spatial \n
fluctuations decay as the temperature is lowered\, manifesting a continuous \n
transition from a Bose glass to BEC.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4358:field_when:0:44
SUMMARY:Probing spin-spin correlations and manipulating exchange interactions in the \n
Van der Waals ferromagnet CrSiTe3
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181129T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181129T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4358
LOCATION:Nano Building 9 th floor Room B991
DESCRIPTION:Speaker: Alon Ron\n
\n
Abstract:\n
Interactions between electrons in solids are responsible for a wide variety \n
of physical phenomena such as magnetism\, superconductivity Mott insulators \n
and more. Understanding interactions between electrons\, and manipulating them \n
to stabilize desired electronic phases have been the research focus of the \n
strongly correlated electrons community in the past few decades. Ultrafast \n
optics is a unique experimental tool where strong ultrashort pulses of light \n
can be used both to probe a multitude of electronic phenomena\, and to excite \n
and manipulate the properties of the electronic system\, driving it away from \n
its equilibrium state. In this talk I will show how ultrafast optical \n
techniques can be used to probe spin spin correlations and modify magnetic \n
interactions in a Van der Waals ferromagnet. CrSiTe3 is composed of van der \n
Waals bonded sheets of ferromagnetically interacting Heisenberg spins that\, \n
in isolation\, would be impeded from long range order by the Mermin-Wagner \n
theorem. I will show that CrSiTe3 evades thislaw via a two-step crossover \n
from two- to three-dimensional magnetic short range order above its Curie \n
temperature (Tc = 31 K)\, manifested through two previously undetected totally \n
symmetric distortions at T2D ~ 110 K and T3D ~ 60 K serving as a direct probe \n
for measuring intarlayer and interlayer spin-spin correlations. Having \n
understood the interplay between short range correlations and the \n
magnetoelastic distortions I will show how optically induced electron \n
transfer could be used to enhance the magnetic super-exchange interaction and \n
how this manipulation can be detected by optically probing generation of \n
coherent phonons.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4357:field_when:0:45
SUMMARY:Universal dynamics of nematic quantum critical metals
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181122T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181122T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4357
LOCATION:Nano Building 9 th floor Room B991
DESCRIPTION:Speaker: Avi Klein (Minnesota)\n
\n
Abstract:\n
Electronic nematicity – spontaneous quadrupole deformation of the \n
electronic dispersion – has been discovered in a variety of strongly \n
correlated quantum materials. Of special interest are metals near a nematic \n
quantum critical point\, such as iron-based superconductors. I will discuss \n
how the non-conservation of a nematic order parameter links long-range \n
quantum fluctuations and short-range anisotropy. This link appears in the \n
nonzero uniform dynamical susceptibility in polarized Raman scattering\, and \n
reveals important microscopic details about the iron-based superconductors. \n
The interplay of long- and short- scales also gives rise to a unique form of \n
superconducting pairing and leads to a highly anisotropic superconducting gap \n
that evolves strongly with temperature.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4359:field_when:0:46
SUMMARY:Quantum Gases in a Box
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181206T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181206T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4359
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Nir Navon (Yale University)\n
\n
Abstract: For the past two decades harmonically trapped ultracold atomic \n
gases have been used with great success to study fundamental many-body \n
physics in a flexible experimental setting. Recently\, we achieved the first \n
atomic Bose-Einstein condensate in an essentially uniform potential of an \n
optical-box trap [1]\, which has opened new possibilities for closer \n
connections with condensed-matter systems and theories of the many-body \n
problem that generally rely on the translational symmetry of the system. I \n
will present recent studies of far-from-equilibrium physics that we have \n
undertaken with this new system: the study of the (Kibble-Zurek) dynamics of \n
spontaneous symmetry breaking in a quenched homogeneous gas [2]\, and the \n
emergence of turbulence in a periodically driven quantum gas [3\,4]. [1] A. \n
L. Gaunt et al.\, Phys. Rev. Lett. 110\, 200406 (2013) [2] N. Navon et al.\, \n
Science 347\, 167 (2015) [3] N. Navon et al.\, Nature 539\, 72 (2016) [4] N. \n
Navon et al.\, arXiv:1807.07564
END:VEVENT
BEGIN:VEVENT
UID:calendar:4356:field_when:0:47
SUMMARY:Selected) Frontiers in plasma science)
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181115T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181115T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4356
LOCATION:Nano Building 9 th floor Room B991
DESCRIPTION:Speaker: (Shurik Yatom (Princeton\n
\n
Abstract:\n
Plasma is a partially of fully ionized gas\, comprising the 99 % of the \n
visible matter in the universe. The physical plasma is scarce in nature on \n
Earth\, however is continuingly gains popularity in the science and technology \n
fields\, since being described by Langmuir in 1920s. Currently\, multiple \n
directions of plasma related research are prominent in a variety of \n
scientific and technological fields: from the quest for fusion energy\, \n
through plasma propulsion for space-travel\, to plasma medicine\, agriculture \n
and material fabrication and functionalization. The potential for \n
applications is indeed vast\, however so are the scientific challenges that \n
emerge in the context of the above applications. In this talk I will \n
concentrate on two exciting areas: plasma-assisted synthesis of nanomaterials \n
and the plasma interactions with liquids\, biological tissues and cells. Both \n
of these research areas are incredibly complex\, owing to multiple different \n
interacting species with a wide variety of energies\, sizes and chemical \n
potentials\, interacting across all the possible phases of matter\, from gas to \n
liquid\, solid and crystal phases\, presenting many exciting physical \n
challenges. Notably\, both these areas consider multiphase environment\, posing \n
many scientific challenges\, such as: large density and temperature\, unknown \n
plasma characteristics\, the control of the reactivity transfer at the \n
plasma–liquid/solid interface\, interfacial charging\, droplet transport and \n
self-organization of plasmas in contact with liquid/solid. Similar challenges \n
occur in the interface of plasma with biological tissues and cells. The \n
phenomenon of plasma self-organization into coherent structures and patterns \n
is particularly interesting\, because it modulates the characteristics of the \n
plasma\, influencing the density and the energy of the charged particles\, \n
chemical composition\, species transport along and across the \n
plasma-tissue/liquid interface\, radiation and electric fields. The aim of \n
this seminar is to introduce these selected frontiers of plasma science\, \n
discuss their promise\, challenges and the experimental approach to their \n
investigation.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4384:field_when:0:48
SUMMARY:Avoiding Ergodicity: Static and Dynamical Localization in Clean Interacting \n
Systems
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181121T120000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181121T130000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4384
LOCATION:Nano (206)\, 9th floor
DESCRIPTION:Speaker: Yuval Baum (Caltech)\n
\n
Abstract:\n
The many body localized phase provides the first and only example of a \n
generic quantum interacting system that does not reach thermal equilibrium\, \n
and thereby violates the most fundamental principles of statistical physics. \n
In the last decade\, an enormous theoretical effort was invested in \n
understanding the nature of this phase. It has attracted a similar deal of \n
attention also within the experimental community\, as it has the potential of \n
storing information about initial states for long times and it allows the \n
application of driving protocols without heating the system to an infinite \n
temperature.\n
\n
A key ingredient for achieving the MBL phase is randomness. The roots of this \n
phase lie within the phenomenon of Anderson localization\, where \n
non-interacting particles form a localized non-ergodic phase. It is the \n
question regarding the fate of Anderson localization in the presence of \n
interactions that plants the seed for the discovery of the MBL phase.\n
\n
We pose the question whether randomness is indeed an essential ingredient in \n
achieving generic non-ergodic interacting phases. We propose the idea that \n
the essential ingredient for MBL is localization\, which does not necessarily \n
mean disorder. We analyze the spectral and the dynamical properties of \n
one-dimensional interacting fermions and spins in the presence of both \n
disorder and linear potential. We show that by considering these two \n
different localizing mechanisms\, i.e.\, disorder and linear fields\, one may \n
construct a two-dimensional phase diagram which hosts a connected non-ergodic \n
(MBL) phase.\n
\n
We also examine the effect of periodic driving on the dynamics of many-body \n
systems and show how such driving provides a general framework for \n
controlling the transport properties in the system\, as well establish mobile \n
composite particles. We demonstrate that by including successive driving \n
terms\, it is possible to completely suppress the motion of particles\, and \n
effectively localize the many-body system\, without the presence of disorder.\n
\n
While at this point we can not make conclusive statements about the nature of \n
this phase in higher dimensions\, the lack of randomness and the low \n
sensitivity to dimensionality may render these systems more accessible to a \n
theoretical investigation in dimensions larger than one. Furthermore\, we make \n
steps towards employing well studied machine learning techniques to address \n
the issue of finite size. Although we don’t show explicitly if it is \n
possible to use such techniques to numerically solve larger system sizes\, we \n
show that a mapping of the disorder realization to the level statistics is \n
easily learned.\n
\n
1. Y. Baum\, Evert P. L. van Nieuwenburg and Gil Refael\, ”From Dynamical \n
Localization to\n
Bunching in interacting Floquet Systems”\, SciPost Phys. 5\, 017 (2018).\n
\n
2. Y. Baum\, Evert P. L. van Nieuwenburg and Gil Refael\, ”From Bloch \n
Oscillations to Many\n
Body Localization in Clean Interacting Systems”\, arXiv:1808.00471 (2018).
END:VEVENT
BEGIN:VEVENT
UID:calendar:4381:field_when:0:49
SUMMARY:Suppressed heating and pre-thermalization in chains of classical kicked \n
rotors
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181108T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181108T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4381
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Atanu Rajak (BIU)\n
\n
Abstract:\n
Periodic drives are a common tool to control physical systems\, but have a \n
limited applicability because time-dependent drives generically lead to \n
heating. How to prevent the heating is a fundamental question with important \n
practical implications. We address this question by analyzing a chain of \n
coupled kicked rotors\, and find two situations in which the heating rate can \n
be arbitrarily small: (i) marginal localization\, for drives with large \n
frequencies and small amplitudes\, (ii) linear stability\, for initial \n
conditions close to a fixed point. In both cases\, we find that the dynamics \n
shows universal scaling laws that allow us to distinguish localized\, \n
diffusive\, and super-diffusive regimes. The marginally localized phase has \n
common traits with recently discovered pre-thermalized phases of many-body \n
quantum-Hamiltonian systems\, but does not require quantum coherence.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4355:field_when:0:50
SUMMARY:Phase Transitions and Topological Transport in Floquet-Bloch systems
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181101T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181101T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4355
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Iliya Esin (Technion)\n
\n
Abstract:\n
Time-periodic driving serves as a promising tool for exploring new phases of \n
quantum matter In particular\, it can be used to induce topological phenomena \n
in conventional\, non-topological systems. In this talk\, I will discuss \n
semiconductors driven with a resonant coherent light – necessary \n
ingredients for the creation of Floquet topological insulators. I will \n
analyze the steady-states emergent in such systems in the presence of natural \n
dissipation mechanisms including phonon-relaxation\, photo-emission and Auger \n
processes\, as well as coupling to external leads. I will show that despite \n
the highly non-equilibrium nature of these systems\, by judicially choosing \n
the properties of the external environments\, their steady states can exhibit \n
some of the hallmark phenomena of contemporary condensed matter: topological \n
transport and phase transitions.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4354:field_when:0:51
SUMMARY:The power of vortices – dual perspectives on exotic quantum phases
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181025T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181025T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4354
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: David Mross (Weizmann)\n
\n
Abstract:\n
The analysis of topological excitations in interacting many-body systems \n
often provides important insights into quantum phases and phase transitions. \n
Seminal examples are the (thermal) BKT transition as well as the (quantum) \n
superfluid-Mott insulator transition\, which are naturally described in terms \n
of vortices. More recently\, such a ‘dual’ formulation has proven \n
extremely illuminating in the study of exotic phases of matter that host \n
fractional excitations\, e.g.\, in topological phases and quantum magnets. In \n
my talk\, I will review the dual description of conventional phases of matter \n
and explain how exotic\, fractionalized phases are captured within this \n
approach. I will then generalize these dualities to fermionic systems\, and \n
discuss the implications for the half-filled Landau level and strongly \n
interacting surfaces of topological insulators. Finally\, I will describe how \n
two-dimensional Dirac fermions (and their symmetries) can be mapped onto \n
interacting bosons.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4335:field_when:0:52
SUMMARY:Electronic transport in low dimensional LaAlO3 /SrTiO3 heterointerface
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181018T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20181018T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4335
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: (Gopi Nath Daptary (BIU\n
\n
Abstract:\n
The large variety of phenomena exhibited by the interface between two \n
band-insulators LaAlO3 and SrTiO3 has attracted intense research activity in \n
recent years. In this talk\, I discuss the results of electronic transport \n
properties of two-dimensional electron gas formed at the LaAlO3/SrTiO3 \n
heterointerface.\n
\n
LaAlO3/SrTiO3 interface exhibits superconductivity at low temperatures. \n
Transport studies reported in this system seem to indicate that the \n
superconductivity is two dimensional in nature\, with a charge carrier density \n
dependent TBKT. We have experimentally studied low frequency resistance \n
fluctuations (noise) and its higher order statistics near the superconducting \n
transition region by varying the temperature\, gate voltage and magnetic \n
field. From the analysis of the higher order statistics of resistance \n
fluctuations\, we find large non-Gaussian components (NGC) in resistance \n
fluctuations appear near TBKT\, which signifies strong correlations among \n
interacting vortices in the system. The NGC are found to be completely absent \n
above TC. Theoretical simulations indicate that the large non-Gaussian \n
resistance fluctuations are manifestation of a percolative transition of a \n
Josephson-coupled superconducting network.\n
\n
LaAlO3/SrTiO3 interface exhibits coexistence of superconductivity and \n
ferromagnetism\, and they are gate tunable. In general\, superconductivity and \n
ferromagnetism are antagonistic to each other. So\, the appearance of two \n
co-existing phase at the interface has opened up a new direction of research \n
in condensed matter physics. In this talk\, I discuss the results of \n
perpendicular magnetic field dependence of sheet resistance above \n
superconducting transition temperature (T/TBKT = 2). From our experiments\, we \n
identify a gate voltage tunable Lifshitz transition in this system. We \n
observed a novel transient superconducting state (TSS) in the presence of a \n
magnetic field applied perpendicular to the interface. We find that the TSS \n
appeared concomitantly with a Lifshitz transition as a consequence of the \n
interplay between ferromagnetism\, superconductivity and the finite relaxation \n
time of the in-plane magnetization in this system.\n
\n
We demonstrate that the resistance fluctuations (noise) have strikingly \n
different features on either side of the Lifshitz transition. Below the \n
Lifshitz transition\, noise is dominated by carrier density fluctuations \n
arising from trapping-detrapping of charge carriers from defects in the \n
underlying SrTiO3 substrate. Above the Lifshitz transition\, we propose that \n
the noise presumably originate from the scattering of carriers from different \n
available conduction channels.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4283:field_when:0:53
SUMMARY:Superconductivity in SrTi1-xNbxO3 under uniaxial strain near a quantum phase \n
transition
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180703T160000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180703T170000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4283
LOCATION:Resnick\, room 210
DESCRIPTION:Speaker: (Ilya Sochnikov (UCONN\n
\n
Abstract:\n
We employed multiple /in situ/ characterization techniques in a dilution \n
refrigerator to probe superconductivity in single crystals of SrTi1-xNbxO3 \n
under continuously tunable strain. We find dramatic changes in the \n
superconducting transition temperature. Microscopic scenarios of this \n
phenomenon will be discussed.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4266:field_when:0:54
SUMMARY:Karen Michaeli
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180524T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180524T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4266
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Karen Michaeli (Weizmann)\n
\n
Abstract:\n
Strongly disordered superconductors in a magnetic field display many \n
characteristic properties of type-II superconductivity— except at low \n
temperatures where an anomalous linear T-dependence of the resistive \n
critical field Bc2 is routinely observed. This behavior violates the \n
conventional theory of superconductivity\, and its origin remains a \n
long-standing puzzle. In a combined experimental and theoretical effort\, we \n
conducted systematic measurements of the critical magnetic field and current \n
on amorphous indium oxide films of various levels of disorder. Surprisingly\, \n
our measurements show that the Bc2 anomaly near zero-temperature is \n
accompanied by a clear mean-field like scaling behavior of the critical \n
current. Theoretically\, we show that these are consequences of the \n
vortex-glass ground state and its thermal fluctuations. This theory further \n
predicts the linear-T anomaly to occur in films as well as bulk \n
superconductors with a slope that depends on the normal-state sheet \n
resistance—in agreement with experimental data. Thus\, our combined study \n
reveals universal low-temperature behavior of Bc2 in a large class of \n
disordered superconductors.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4200:field_when:0:55
SUMMARY:The Gas Liquid Transition of Excitons
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180531T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180531T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4200
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: (Israel Bar-Joseph(weizmann\n
\n
Abstract:\n
In this talk I shall review our work on the gas-liquid transition of 2D \n
excitons in GaAs quantum wells. Below a critical temperature and above a \n
critical density this system undergoes a phase transition to a liquid state. \n
By employing a variety of optical spectroscopy tools we map the phase diagram \n
of the system and show that the liquid is a Bose Einstein condensate. We find \n
that the excitons condense in the lowest energy state which is not coupled to \n
light (“dark excitons”).
END:VEVENT
BEGIN:VEVENT
UID:calendar:4191:field_when:0:56
SUMMARY:The nature of the phase transition in La1.875Sr0.125CuO4 as determined by the \n
Stiffnessometer - a magnetic-field-free superconducting stiffness meter
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180607T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180607T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4191
LOCATION:Reznik Building 209 room 210
DESCRIPTION:Speaker: (Amit Keren(Technion\n
\n
Abstract:\n
A new method to measure the superconducting stiffness tensor \, without \n
subjecting the sample to magnetic field\, is applied to \n
La1.875Sr0.125CuO4 (LSCO). The method is based on the London equation \, \n
where is the current density and is the vector potential. Using rotor \n
free and measuring via the magnetic moment of superconducting rings\, we \n
extract . The technique\, named Stiffnessometer\, is sensitive to very small \n
stiffness\, which translates to penetration depth on the order of a few \n
millimeters. We apply this method to two different LSCO rings: one with the \n
current running only in the CuO2 planes\, and another where the current must \n
cross planes. We find different transition temperatures for the two rings\, \n
namely\, there is a temperature range with two-dimensional stiffness. The \n
Stiffnessometer results are accompanied by Low Energy mSR measurements on \n
the same sample to determine the stiffness anisotropy at favorable \n
temperatures.\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4227:field_when:0:57
SUMMARY:Doped Kondo chain\, a heavy Luttinger liquid
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180621T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180621T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4227
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: (Ilia Khait(Technion\n
\n
Abstract:\n
The doped 1D Kondo Lattice describes complex competition between itinerant \n
and magnetic ordering. The numerically computed wave vector-dependent charge \n
and spin susceptibilities give insights into its low-energy properties. \n
Similar to the prediction of the large N approximation\, gapless spin and \n
charge modes appear at the large Fermi wave vector. The highly suppressed \n
spin velocity is a manifestation of “heavy” Luttinger liquid \n
quasiparticles. A low-energy hybridization gap is detected at the small \n
(conduction band) Fermi wave vector. In contrast to the exponential \n
suppression of the Fermi velocity in the large-N approximation\, we fit the \n
spin velocity by a density-dependent power law of the Kondo coupling. The \n
differences between the large-N theory and our numerical results are \n
associated with the emergent magnetic Ruderman–Kittel–Kasuya–Yosida \n
interactions.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4212:field_when:0:58
SUMMARY:Quantization of heat flow in the fractional quantum Hall regime
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180614T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180614T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4212
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Mitali Banerjee - (Weizmann)\n
\n
Abstract:\n
Quantum mechanics sets an upper bound on the amount of charge flow as well \n
as on the amount of heat flow in ballistic onedimensional channels. The two \n
relevant upper bounds\, which combine only fundamental constants\, are the \n
quantum of the electrical conductance\, Ge=e2/h\, and the quantum of the \n
thermal conductance\, Gth=κ0T=(π2kB2/3h)T. Remarkably\, the latter does not \n
depend on the particles charge\, particles exchange statistics\, and is \n
expected also to be insensitive to the interaction strength among the \n
particles. However\, unlike the elative ease in observing the quantization \n
of the electrical conductance\, measuring accurately the thermal conductance \n
is more challenging.\n
\n
The universality of the Gth quantization in 1D ballistic channels was \n
demonstrated for weakly interacting particles: phonons [1]\, photons [2]\, and \n
in an electronic Fermi-liquid [3]. I will describe our recent experiments \n
with heat flow in a strongly interacting system of 2D electrons in the \n
fractional quantum Hall regime. In the lowest Landau level we studied \n
particle-like states (v<½) and the more complex hole like states (½th=κ0T \n
in all these abelian states. In the first-excited Landau level (2th=½κ0T\, a \n
definite mark of a non-abelian state harboring Majorana excitations [5].\n
\n
1. K. Schwab\, et al.\, Nature 404\, 974 (2000)\n
2. M. Meschke\, et al.\, Nature 444\, 187 (2006)\n
3. S. Jezouin\, et al.\, Science 342\, 601 (2013)\n
4. M. Banerjee et. al.\, Nature 545\, 75 (2017)\n
5. M. Banerjee et. al.\, arXiv: 1710.00492\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4199:field_when:0:59
SUMMARY:Topological materials and topological responses
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180517T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180517T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4199
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: (Binghai Yan(Weizman\n
\n
Abstract:\n
The past decade has witnessed intensive research aimed at investigating the \n
role of band-structure topology and discovering topological materials. The \n
topology provides a new aspect to understand the band-structure and reveal \n
exotic phenomena\, such as topological surface states. In this talk\, I will \n
focus on recently-discovered Weyl semimetals. Besides the unique Fermi arc \n
surface states\, I will introduce the transport and optical phenomena in \n
realistic materials\, which include the linear response (e.g. anomalous Hall \n
and spin Hall effects) and nonlinear response (second-harmonic generation and \n
dc photocurrents) induced by the Weyl band structure.\n
\n
Refs. Annu. Rev. Condens. Matter Phys. 8\, 337-354 (2017)\; Nature \n
Physics *11*\, 728 (2015)\; arXiv:1708.08589\, and arXiv:1803.00562.\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4192:field_when:0:60
SUMMARY:Finite-Momentum Superconducting State Generated by Electromagnetic Radiation
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180426T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180426T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4192
LOCATION:Reznik Building 209 room 210
DESCRIPTION:Speaker: (Yehuda Dinaii (Weizmann\n
\n
Abstract: When a superconductor is subjected to electromagnetic radiation\, \n
characteristic quantities such as the magnitude of the gap may assume higher \n
values than those assumed under equilibrium conditions. Intensive theoretical \n
and experimental studies of this so-called superconductivity \n
stimulation have culminated in many insights and a puzzle: the theoretically \n
resulting state is unstable with respect to infinitesimal fluctuations. A \n
resolution to this problem is proposed here in the form of a moving \n
condensate. Derivation and solution of the appropriate kinetic equation \n
yields a family of locally stable states supporting finite superfluid \n
velocity and current. These findings can be tested experimentally with \n
existing techniques and suggest a novel way to detect microwave photons.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4197:field_when:0:61
SUMMARY:Laughlin-like states in ladder setups
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180315T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180315T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4197
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Marcello Calvanese Strinati - BIU\n
\n
Abstract:\n
The combination of interactions and static gauge fields plays a pivotal role \n
in our understanding of strongly correlated quantum matter. Cold atomic gases \n
endowed with a synthetic dimension are emerging as an ideal platform to \n
experimentally address this interplay in quasi-one-dimensional systems. A \n
fundamental question is whether these setups can give access to pristine \n
two-dimensional phenomena\, such as the fractional quantum Hall effect\, and \n
how. We show that unambiguous signatures of bosonic and fermionic \n
Laughlin-like states can be observed and characterized in synthetic ladders. \n
We theoretically diagnose these Laughlin-like states focusing on the chiral \n
current flowing in the ladder\, on the central charge of the low-energy \n
theory\, and on the properties of the entanglement entropy.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4204:field_when:0:62
SUMMARY:The phase diagram of (111) SrTiO3/LaAlO3 interfaces
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180322T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180322T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4204
LOCATION:Reznik Building 209 room 210
DESCRIPTION:Speaker: Yoram Dagan - School of Physics and Astronomy\, Tel Aviv University\n
\n
Abstract:\n
The two dimensional electron liquid formed at the (111) interface between \n
SrTiO3 and LaAlO3 is\n
a laboratory for studying electronic properties in tunable correlated \n
hexagonal systems.\n
Symmetry changes imposed by the interface and by various structural \n
transitions in the bulk can\n
affect the electronic properties at the interface. In addition\, this system \n
can be smoothly tuned\n
from the superconductor deep into the insulator regime.\n
The normal state properties of the (111) LaAlO3/SrTiO3 interface are \n
indicative of contributions\n
from electron-type and hole-type charge carriers. The latter are also \n
consistent with the polar\n
structure of this interface. Upon applying gate voltage to add electrons\, a \n
band with a higherspin\n
state gets populated\, resulting in a six-fold anisotropic magnetoresistance \n
[1].\n
Superconductivity is observed in a dome-shaped region in the carrier density \n
– temperature\n
\n
phase diagram. The upper critical field is strongly anisotropic and exceeds \n
the Clogston-\n
Chandrasekhar limit. This suggests strong spin-orbit interaction so. \n
Surprisingly\, so is also\n
\n
nonmonotonic as a function of gate voltage as found both from analysis of the \n
superconducting\n
properties and of the weak antilocalization measurements [2].\n
Finally\, in the depleted region we can probe the highly insulating regime\, \n
where the sheet\n
resistance is significantly larger than the quantum one. Despite the large \n
resistance\, the\n
interface exhibits the sharp increase in resistance under applied magnetic \n
field characteristic of\n
a superconductor to insulator transition. By use of electrostatic gating and \n
magnetic fields\, the\n
sample is tuned from the metallic region\, where supeconductivity is fully \n
manifested\, deep into\n
the insulating state. Through examination of the field dependence of the \n
sheet resistance and\n
comparison of the response to fields in different orientations we show that \n
vortex-like\n
fluctuations are responsible for the transition in this material and that \n
these fluctuations persist\n
deep into the insulating state [3].\n
\n
[1] P.K. Rout\, I. Agireen\, E. Maniv\, M. Goldstein\, Y. Dagan Physical Review B \n
95 (24)\, 241107\n
[2] P.K. Rout\, E. Maniv\, Y. Dagan\, arXiv:1706.01717 (Accepted in Phys. Rev. \n
Lett.)\n
[3] M. Mograbi et al. To be published somewhere but not in Nature.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4183:field_when:0:63
SUMMARY:Superfluidity in Bose-Hubbard circuits
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180308T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180308T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4183
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Geva Arwas (BGU)\n
\n
Abstract:\n
The essence of superfluidity is the possibility to witness metastable flow \n
states. In the standard classical stability analysis\, one finds that flow \n
states whose rotation velocity is less than a critical velocity are \n
metastable (“Landau criterion”). In this talk I will show that the \n
standard superfluidity criteria fail in low-dimensional circuits and that a \n
proper determination of the superfluidity regime-diagram requires a quantum \n
chaos perspective. In particular\, I will explain the drastic differences \n
between three-site rings and rings that have more than three sites. In the \n
former\, instability of flow states is due to a swap of separatrices\, while in \n
the latter it has to do with a web of non-linear resonances.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4132:field_when:0:64
SUMMARY:Thermodynamics of small quantum systems and small environments
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180118T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180118T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4132
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Raam Uzdin (Technion)\n
\n
Abstract:\n
With the rapid development of quantum technologies and the ability to \n
manipulate individual atoms and ion\, thermodynamics faces new challenges. The \n
main question is not whether thermodynamics is valid\, but whether it is \n
relevant. Does it provide useful predictions on quantities of interest in the \n
microscopic world? By introducing the concept of global passivity we derive \n
an extension of the second law of thermodynamics that can properly handle \n
initial quantum correlations (i.e.\, entanglement\, and quantum discord) \n
between the system and the environment. This extension is very important in \n
nanoscopic setups where the environment may be small and strongly interacting \n
with the system of interest. A second main finding of this framework is a \n
family of additional thermodynamic relations that involve measurable \n
quantities that were so far not constrained by thermodynamics. In particular\, \n
we use these relations to set upper and lower bounds on the buildup of \n
system-environment correlation in quantum dephasing scenarios (decoherence). \n
As a second example\, we study the evolution of energy covariance between an \n
atom and an optical cavity. Our findings are highly relevant for various \n
modern experimental setups such as ion traps\, atoms in an optical cavity or \n
in optical lattices\, and more.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4059:field_when:0:65
SUMMARY:Nanoscale magnetic and thermal imaging in quantum systems
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180125T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180125T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4059
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Yonathan Anahory (Jerusalem)\n
\n
Abstract:\n
NanoSQUIDs residing on the apex of a quartz tip (SOT)\, suitable for scanning \n
probe microscopy with record size\, spin sensitivity\, and thermal sensitivity \n
are presented[1\,2] . We have developed SOT with an effective diameter smaller \n
than 50 nm\, spin sensitivity better than a single electron spin and thermal \n
sensitivity better than 1 μK/Hz1/2 . This technique is used to study \n
nanoscale magnetism present in systems such as atomically sharp LaMnO3/SrTiO3 \n
(LMO/STO) heterostructures[3] and to study dissipation mechanism in quantum \n
system such as hBN-encapsulated graphene[2\,4] . Magnetic imaging of LMO/STO \n
revealed a superparamagnetic behavior resulting from an electronic phase \n
separation leading to nucleation of metallic ferromagnetic islands in an \n
insulating antiferromagnetic matrix. Thermal imaging of hBN-encapsulated \n
graphene reveals a fascinating atomic-scale dissipation mechanism providing \n
visualization and control of phonon emission from inelastic electron \n
scattering off individual atomic defects[4] \, opening the door to direct \n
imaging and spectroscopy of dissipation processes in quantum systems.\n
\n
\n
\n
[1] D. Vasyukov\, Y. Anahory\, L. Embon\, D. Halbertal\, J. Cuppens\, L. Neeman\, \n
A. Finkler\, Y. Segev\, Y. Myasoedov\, M. L. Rappaport\, M. E. Huber\, and E. \n
Zeldov\, Nature Nanotech. 8\, 639 (2013)\n
\n
[2] D. Halbertal\, J. Cuppens\, M. Ben Shalom\, L. Embon\, N. Shadmi\, Y. Anahory\, \n
H. R. Naren\, J. Sarkar\, A. Uri\, Y. Ronen\, Y. Myasoedov\, L. S. Levitov\, E. \n
Joselevich\, A. K. Geim\, and E. Zeldov\, Nature 539\, 407 (2016).\n
\n
[3] Y. Anahory\, L. Embon\, C. J. Li\, S. Banerjee\, A. Meltzer\, H. R. Naren\, A. \n
Yakovenko\, J. Cuppens\, Y. Myasoedov\, M. L. Rappaport\, M. E. Huber\, K. \n
Michaeli\, T. Venkatesan\, and E. Zeldov\, Nature Communications 8\, 85 (2016)\n
\n
[4] D. Halbertal\, M. Ben Shalom\, A. Uri\, K. Bagani\, A.Y. Meltzer\, I. Marcus\, \n
Y. Myasoedov\, J. Birkbeck\, L.S. Levitov\, A.K. Geim\, and E. Zeldov\, Science \n
358\, 1303 (2017).
END:VEVENT
BEGIN:VEVENT
UID:calendar:4124:field_when:0:66
SUMMARY:Two Universalities in Semiconductor Physics
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180510T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180510T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4124
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Michael Wilkinson (Open University\, UK)\n
\n
Abstract:\n
I shall give theoretical explanations of two surprising experimental \n
observations of universal behaviour in semiconductor systems.\n
The fist concerns the dependence of photoconductivity $G$ upon light \n
intensity $I$. It is typically found that $G=I^\gamma$. Simple kinetic theory \n
indicates that we should expect $\gamma=1$ or $\gamma=1/2$\, but \n
experimentally values close to $\gamma =3/4$ or $\gamma=2/3$ are often \n
observed\, with $I$ varying over several decades. I shall present a new \n
explanation for these universal exponents.\n
The second universality concerns exciton spectroscopy in heterostructures. \n
The linewidth $W$ of the absorption line and the Stokes shift $S$ of the \n
luminescence peak relative to the absorption peak are found to be related by \n
$S/W=0.6$ in most systems for which both values are published. This ratio is \n
independent of the degree of disorder and of the composition of the \n
semiconductors forming the heterostructure\, with $W$ varying over two \n
decades. I shall also give a quantitative explanation of this result.\n
\n
Finally I point out what these two phenomena have in common.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4058:field_when:0:67
SUMMARY:Van-der-Waals integration of superconducting tunneling devices
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180111T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180111T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4058
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Hadar Steinberg (Hebrew University)\n
\n
Abstract:\n
Layered materials can be exfoliated to very thin films. In our group we \n
utilize a technique called “mechanical transfer”\, which allows stacking \n
of such materials into new types of heterostructures which can involve layers \n
of distinct functionalities. In my talk I will describe this fabrication \n
technique\, and demonstrate how we build a new type of device which consists \n
of a layered superconductor (NbSe2)\, on which we deposit an ultra-thin layer \n
of the semiconductor WSe2. Together\, these two materials form a tunneling \n
device\, which can be cooled to extremely low temperatures (20 mK) in a \n
dilution cryostat fitted with special filters which allow very sensitive \n
energy spectroscopy. Our tunneling spectra allow tracking the evolution of \n
the superconductor order parameter at the presence of strong magnetic fields\, \n
and quantifying its stability. Specifically\, the depairing energy scale can \n
be evaluated\, and its origin – orbital or spin – identified. Thus\, we are \n
able to identify which of the two bands participating in NbSe2 \n
superconductivity is associated with this material’s remarkable stability \n
against in-plane magnetic field.\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4056:field_when:0:68
SUMMARY:Emergent Finite Frequency Criticality of Driven-Dissipative Correlated \n
Lattice Bosons
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171214T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171214T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4056
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Marco Schirò (CNRS)\n
\n
Abstract: \n
We study dynamical and steady-state dissipative quantum phase transitions of \n
a driven Bose Hubbard model between an incoherent Mott-like insulating phase \n
and a non-equilibrium superfluid. We highlight the crucial role of pumping \n
scheme and the unique features that emerge in the driven- dissipative case as \n
compared to the well known equilibrium quantum criticality. These results \n
might be relevant for the upcoming generation of circuit QED arrays \n
experiments aiming at realizing Mott Insulator of Polaritons and its \n
transition into a nonequilibrium superfluid.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4055:field_when:0:69
SUMMARY:The Ergodic Side of the Many-Body Localization Transition
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171207T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171207T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4055
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Yevgeny Bar Lev (Weizmann)\n
\n
Abstract:\n
Generic interacting\, disordered and isolated systems were shown to break \n
ergodicity in a dynamical transition\, called the many-body localization \n
transition. In this talk I will survey the anomalous dynamical properties of \n
the ergodic phase and will present a phenomenological picture which was \n
proposed to explain them. I will provide evidence which suggest that this \n
picture might not be complete.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4088:field_when:0:70
SUMMARY:Photocurrents in a topological insulator - an inside view
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180104T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180104T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4088
LOCATION:Reznik Building 209 room 210
DESCRIPTION:Speaker: Hadas Soifer (Stanford)\n
\n
Abstract:\n
Topological insulators have been in the focus of condensed-matter research in \n
recent years. In particular\, much effort was dedicated to optically excite \n
and control currents involving the topological surface states. We image the \n
unoccupied bandstructures of a topological insulator as it evolves following \n
an optical excitation\, and observe the signature of a photo-induced current. \n
By applying a time-mapping analysis we gain a complete view on the occupied \n
and unoccupied electronic states\, and how they are coupled by the optical \n
excitation. This enables us to determine that photocurrents are excited only \n
via the resonant optical transitions\, paving the way to optical control of \n
currents in topological insulators.\n
\n
END:VEVENT
BEGIN:VEVENT
UID:calendar:4038:field_when:0:71
SUMMARY:HgTe quantum wells. Energy spectrum and transport phenomena. \n
Theory-versus-experiment.
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180107T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20180107T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4038
LOCATION:Resnick Building 209\, room 210 ** * NOTE UNUSUAL DAY ***
DESCRIPTION:Speaker: Grigori Minkov (Ural Federal University)\n
\n
Abstract:\n
I plan to make a short review of the features of the energy spectrum of \n
carriers in the quantum wells of a gapless semiconductor HgTe\, in which\, \n
depending on the thickness of the well\, the "normal"\, inverted and \n
semimetallic spectra are realized. I will review the edge\, topologically \n
protected states\, that should arise in structures with an inverted spectrum \n
(which is realized at a quantum well thickness greater than d_c = 6.3 nm.\n
\n
In more detail\, I will discuss the current state of experimental results on \n
the study of the energy spectrum\, the role of edge states in kinetic \n
effects. For a real understanding of any experimental results the reliable \n
knowledge of the energy spectrum is necessary. Theoretically\, it has been \n
studied quite well and in detail. However\, by the present time\, quite a lot \n
of contradictions have accumulated between theory and experiment. Therefore\, \n
our main attention will be paid to our experimental studies of the spectrum \n
of the valence band in structures with a well thickness close to d_c and with \n
d> d_с [1\,2\,3]. It will be shown that interface inversion asymmetry leads \n
to a large spin-orbit splitting\, which radically changes the spectrum of the \n
valence band.\n
\n
--------------------\n
\n
1. G. M. Minkov\, A. V. Germanenko\, O. E. Rut\, A. A. Sherstobitov\, M. O. \n
Nestoklon\, S. A. Dvoretski\, and N. N. Mikhailov\, Spin-orbit splitting of \n
valence and conduction bands in HgTe quantum wells near the Dirac point\, \, \n
Phys. Rev. B 93\, 155304 – Published 11 April 2016.\n
\n
2. G. M. Minkov\, V. Ya. Aleshkin\, O. E. Rut\, A. A. Sherstobitov\, A. V. \n
Germanenko\, S. A. Dvoretski\, and N. N. Mikhailov\, Valence band energy \n
spectrum of HgTe quantum wells with an inverted band structure\, Phys. Rev. B \n
96\, 035310 (2017) - Published 26 July 2017\n
\n
3. G.M. Minkov et al\, Conductance of a Lateral p–nJunction in \n
TwoDimensional HgTe Structures with an Inverted Spectrum: The Role of Edge \n
States JETP Letters\, 2015\, Vol. 101\, No. 7\, pp. 469–473\, 2015
END:VEVENT
BEGIN:VEVENT
UID:calendar:4053:field_when:0:72
SUMMARY:Realizing quantum spin liquid phases in spin-orbit driven correlated \n
materials
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171123T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171123T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4053
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Gidon Wachtel (HUJI + University of Toronto)\n
\n
Abstract:\n
The spin liquid phase is one of the prominent strongly interacting \n
topological phases of matter whose unambiguous confirmation is yet to be \n
reached despite intensive experimental efforts on numerous candidate \n
materials. The challenge is derived from the difficulty of formulating \n
realistic theoretical models for these materials and interpreting the \n
corresponding experimental data. Here we study a theoretical model with \n
bond-dependent interactions\, directly motivated by recent experiments on \n
two-dimensional correlated materials with strong spin-orbit coupling. We show \n
numerical evidence for the existence of an extended family of quantum spin \n
liquids\, which are possibly connected to the Kitaev spin liquid state. These \n
results are used to provide an explanation of the scattering continuum seen \n
in neutron scattering on α-RuCl.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4081:field_when:0:73
SUMMARY:Electron magnetotransport in disordered Weyl semimetals
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171122T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171122T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4081
LOCATION:*** Nano 9th floor *** NOTE THE DIFFERENT DAY AND LOCATION
DESCRIPTION:Speaker: Pavel Ostrovsky\n
\n
Abstract:\n
We study magnetotransport in a disordered Weyl semimetal taking into \n
account localization effects. In the vicinity of a Weyl node\, a single \n
chiral Landau level coexists with a number of conventional non-chiral \n
levels. Disorder scattering mixes these topologically different modes \n
leading to peculiar localization effects. Similar interplay of topology \n
and localization occurs at the edge of a two-dimensional topological \n
insulator and in carbon nanotubes. We develop a general theory \n
describing transport phenomena in all these cases. Our theory yields \n
conductance\, shot noise power\, and full counting statistics of the \n
charge transfer. In the case of a Weyl semimetal\, we find that \n
localization is greatly enhanced in a strong magnetic field with the \n
typical localization length scaling as 1/B. This situation is typical \n
for all topological conductors with broken time-reversal symmetry. \n
Systems with preserved time-reversal symmetry (e.g.\, carbon nanotubes)\, \n
sustain at most one topologically protected channel. For this case\, we \n
derive exact distribution function of transmission probabilities based \n
on the mapping to a certain random-matrix model.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4052:field_when:0:74
SUMMARY:Topological Josephson Junctions
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171102T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171102T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4052
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Tamar Pereg Barnea (McGill)\n
\n
Abstract:\n
The Josephson effect in conventional superconductors has led to a variety of \n
extensions and applications from SQUID magnetometers to pairing symmetry \n
detection using planar junctions. It is therefore interesting to extend the \n
discussion to topological Josephson junctions where Majorana fermions\, and \n
not just Cooper pairs\, can tunnel through the junction. In this talk I will \n
consider a setup made of a ring of topological superconducting wires \n
separated by Junctions and coupled to a quantum dot. The coupling to the \n
quantum dot serves as a knob which tunes the periodicity of the current in \n
the junction as a function of external flux. The periodicity can change \n
from one flux quantum (h/2e)\, expected from a conventional junction\, to that \n
of a topological junction\, h/e. This tuning ability can distinguish between a \n
topological junction and a dirty non-topological junction. I will also \n
discuss phase slips and the suppression of 2pi phase slips in topological \n
Josephson junctions.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4075:field_when:0:75
SUMMARY:Magnetic imaging of skyrmions in a thin film
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171130T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171130T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4075
LOCATION:Resnick\, room 210
DESCRIPTION:Speaker: Ophir Auslaender (Technion)\n
\n
Abstract:\n
Magnetic skyrmions are topologically protected\, nanoscale\, whorls and \n
hedgehogs of magnetization. Because of their topological properties skyrmions \n
also give rise to novel phenomena such as the topological Hall effect. Low \n
temperature magnetic force microscopy (MFM) provides us with a tool for both \n
imaging and control of skyrmions. Here I will describe recent experiments on \n
multilayer Ir/Fe/Co/Pt stacks which can host Néel (hedgehog) skyrmions. We \n
use MFM to image the magnetic structure in the films as a function of \n
temperature and magnetic field. This allows us to explore the correspondence \n
between the topological Hall effect and the magnetic textures that we image. \n
For the analysis we rely on a new simple model for the magnetic field from a \n
skyrmion.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4074:field_when:0:76
SUMMARY:Visualizing "Fermi arcs" and their properties in the Weyl semimetal TaAs
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171109T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171109T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4074
LOCATION:Resnick\, room 210
DESCRIPTION:Speaker: Nurit Avraham (Weizmann)\n
\n
Abstract: One of the hallmarks of Weyl semi-metals is the existence of \n
unusual topological surface states known as "Fermi arcs". The formation of \n
these states is guaranteed by the existence of bulk Weyl points with opposite \n
chirality. Tantalum Arsenide (TaAs)\, a member of the newly discovered family \n
of Weyl semi-metals\, harbors a host of non-topological (“trivial”) \n
surface states overlapping in energy with the 12 predicted topological "Fermi \n
arcs". This overlap poses a major challenge in identifying the signatures of \n
the arcs. We use scanning tunneling microscopy to address this challenge. In \n
my talk I will show how we harness the inherently distinct spatial structure \n
of trivial and Fermi arc states to isolate the Fermi arcs and to visualize \n
them by quasi particle interference (QPI) measurements [1]. We do so in four \n
distinct ways\, each of which highlights a different aspect of their unusual \n
nature - we reveal their relatively isotropic scattering signature\, their \n
energy dispersion and its relation to the bulk Weyl points\, their deep bulk \n
penetration relative to that of non-topological surface states and their weak \n
coupling to the atomic structure. The latter is obtained by accounting for \n
the spatial structure of the Bloch wave function and its effect on the \n
scattering properties of the electrons off lattice defects. I will discuss \n
the role of the Bloch wave function structure in understanding QPI \n
measurements and show that it provides a novel analysis tool for the \n
spectroscopic characterization of electronic wave functions using scanning \n
tunneling microscopy. \n
[1] http://advances.sciencemag.org/content/2/8/e1600709 [1])\n
\n
\n
[1] http://advances.sciencemag.org/content/2/8/e1600709
END:VEVENT
BEGIN:VEVENT
UID:calendar:4051:field_when:0:77
SUMMARY:Bilayer graphene as a playground for exotic magnetic phases
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171026T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171026T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4051
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Efrat Shimshoni (Bar-Ilan)\n
\n
Abstract:\n
Bilayer graphene subjected to magnetic and electric fields exhibits a \n
plethora of phases with radically distinct behaviors. Most prominently\, the \n
\nu=0* *quantum Hall state which develops at zero doping manifest a rich \n
phase diagram marked by changes in the electrical conductance\, and is tunable \n
by either of the external fields. This behavior is attributed to the variety \n
of many-body states with broken symmetry\, which can form due to the \n
multi-component nature of the discrete degrees of freedom (spin\, valley and \n
orbital isospin). In particular\, in the presence of a perpendicular electric \n
field D\, at least two distinct insulating phases are identified: a canted \n
antiferromagnet (CAF) at low D\, and a fully layer polarized (FLP) phase at \n
low D. However\, at intermediate values of D and the magnetic field B\, a \n
finite conductance is developed\, potentially indicating the formation of \n
novel intermediate phases. I present a theoretical study motivated by these \n
observations\, which accounts for the interplay between lattice-scale \n
interactions\, inherently anisotropic in the spin-valley-orbital manifold\, and \n
a (formerly overlooked) trigonal warping effect in the electronic \n
band-structure. Employing a Hartree-Fock calculation\, we find several \n
competing many-body states characterized by unusual spin-valley entangled \n
correlations\, which are promising candidates for the ground-state at \n
intermediate fields. Most interestingly\, we find a regime of parameters where \n
the emergent intermediate phase is characterized by a simultaneous breaking \n
of two distinct U(1) symmetries. I further discuss the implications on \n
transport properties\; most remarkably\, the emergence of high conductance is a \n
possible signature of robust collective edge modes associated with textures \n
in the spin/valley manifold\, which are topological in nature.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4050:field_when:0:78
SUMMARY:Superconductivity at ultra low-densities
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171116T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171116T123000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4050
LOCATION:Resnick (#209) - room 210
DESCRIPTION:Speaker: Jonathan Ruhman (MIT)\n
\n
Abstract:\n
Over the past 5 years or so\, superconductivity has been observed in a number \n
of different materials with an extremely low density of charge carriers. \n
Some of these are even among the most dilute metals that exist\, such as \n
SrTiO3 and bismuth. In this limit\, the screening of the Coulomb repulsion is \n
poor\, and moreover\, the conventional phonon mechanism for superconductivity \n
is completely irrelevant. This raises the question: how can these materials \n
be superconducting? I will propose two different mechanisms for \n
superconductivity in low-density metals\, based on dynamically screened \n
Coulomb interactions and fluctuations near a structural quantum critical \n
point. I will further discuss the prospects of these mechanisms for \n
topological superconductivity and superconductivity in two-dimensional \n
materials.
END:VEVENT
BEGIN:VEVENT
UID:calendar:4039:field_when:0:79
SUMMARY:Anomalous Hall effect with massive Dirac fermions
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171002T120000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20171002T120000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/4039
LOCATION:Reznik building\, seminar room
DESCRIPTION:Speaker: Dr. Pavel Ostrovsky\, Max Planck Institute\, Stuttgart\n
\n
Abstract:\n
The anomalous Hall effect arises in systems with both spin-orbit coupling \n
and magnetization.\n
We study the minimal model of the anomalous Hall effect based on the massive \n
Dirac Hamiltonian and consider two \n
limiting cases of weak (Gaussian) and strong (Poisson) impurities.\n
The standard diagrammatic approach to the problem is limited to computation \n
of ladder diagrams.\n
We demonstrate that this is insufficient in the case of Gaussian disorder. \n
An important additional contribution comes from \n
scattering on pairs of closely located defects and essentially \n
modifies previously obtained results for anomalous Hall conductivity.\n
n the case of Poisson disorder\, we go beyond semiclassical limit and \n
calculate weak \n
localization corrections. Unlike the case of ordinary Hall effect\, \n
we identify a finite quantum correction to anomalous Hall resistivity. \n
Depending on the structure of impurities\, this correction can have any sign \n
and interpolates smoothly between universal orthogonal \n
(localization) and symplectic (antilocalization) limits.
END:VEVENT
BEGIN:VEVENT
UID:calendar:3998:field_when:0:80
SUMMARY:Currents and Phases in Quantum Rings
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20170622T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20170622T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/3998
LOCATION:9th floor of the Nanotechnology building
DESCRIPTION:Speaker: Kathryn Moler (Stanford)\n
\n
Abstract:\n
The current that flows in a ring can be a signature of fundamental and \n
topological properties of quantum states of charge-carrying particles. \n
Applying a magnetic flux through a ring creates a phase gradient\, in \n
response to which a current flows\, creating magnetic fields that we measure \n
with a scanning SQUID microscope. I will take you on a tour of currents and \n
phases in common and exotic quantum materials. Gold rings are normal metals \n
with finite resistance\, but remarkably\, they carry persistent currents whose \n
sign and magnitude confirm the quantum behavior of disordered metals. \n
Aluminum rings superconduct at low temperatures\, and are an ideal model \n
system to study superconducting fluctuations. The strong agreement of theory \n
and experiment in conventional metals and superconductors sets the stage to \n
study superconducting rings interrupted by a single Josephson junction. This \n
geometry allows us to measure a fundamental and informative property of the \n
junction\, called the current-phase relation. In junctions made of topological \n
materials\, the current could theoretically be 4pi-periodic rather than \n
2pi-periodic as a function of the phase winding in the ring. I will report \n
on progress towards this smoking-gun signature for Majorana modes.
END:VEVENT
BEGIN:VEVENT
UID:calendar:3964:field_when:0:81
SUMMARY:Geometrically frustrated mechanical metamaterials
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20170608T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20170608T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/3964
LOCATION:Nano (#206) - 9th floor
DESCRIPTION:Speaker: Yair Shokef (TAU)\n
\n
Abstract:\n
N/A
END:VEVENT
BEGIN:VEVENT
UID:calendar:3965:field_when:0:82
SUMMARY:Current aspects of topological superconductivity
DTSTAMP;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20200601T023949
DTSTART;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20170629T123000
DTEND;TZID=Asia/Tel_Aviv;VALUE=DATE-TIME:20170629T133000
URL;VALUE=URI:https://physics.biu.ac.il/en/node/3965
LOCATION:Nano (#206) - 9th floor
DESCRIPTION:Speaker: Arbel Haim (Weizmann)\n
\n
Abstract:\n
Recent experiments have provided mounting evidence for the existence of \n
Majorana\n
bound states (MBSs) in condensed-matter systems. Until the long-term goal of \n
braiding MBSs is\n
achieved\, one is prompted to ask: what is the next step in the study of \n
topological\n
superconductivity and MBSs? In my talk I will discuss two topics relating to \n
this question. In the\n
first part I will examine the possibility of\, not only detecting the \n
Majoranas\, but also witnessing\n
some of their exotic properties. In particular their non-local nature\, or in \n
other words\, the fact that\n
the MBS is half a fermion whose occupation is encoded in a nonlocal way. I \n
will show that current\n
cross correlations in a T-junction with a single MBS exhibit universal \n
features\, related to the\n
Majorana nonlocality. This will be contrasted with the case of an accidental \n
low-energy Andreev\n
bound state. In the second part I will discuss the possibility of realizing a \n
different topological\n
phase hosting MBSs in currently available experimental platforms. This will \n
be a topological\n
superconducting phase which is protected by time-reversal symmetry\, and which \n
is characterized\n
by having a Kramers’ pair of MBSs at each end. As I will discuss\, repulsive \n
interactions are a\n
necessary ingredient for the realization of this phase. I will present a \n
mechanism\, based on the\n
interplay between repulsive interactions and proximity to a conventional \n
superconductor\, which\n
drives the system into the topological phase. The effect of interactions is \n
studied analytically using\n
both a mean-field approach and the renormalization group. We corroborate our \n
conclusions\n
numerically using DMRG.\n
END:VEVENT
END:VCALENDAR