Strong interactions in correlated dipolar quantum fluids of excitons and polaritons

Quantum fluids of matter with long range, anisotropic interactions display rich excotic collective phenomena, from Roton instabilities, quantum droplets, and supersolidity [1]. A prominent example is the dipole-dipole interaction, which has recently been addressed by a growing community, both from atomic physics as well as from condensed matter physics, with the latter being focused on dipolar quantum fluids of two-dimensional excitons, bound pairs of an electron and  a hole in a semiconductor. Very recently, interacting dipolar polaritons, which dressed superposition states of dipolar excitons and confined photons have been reported. These strongly interacting dipolar exciton and polariton systems offer opportunities to explore new collective phenomena which are currently inaccessible with atomic dipolar gases, and the possibility to demonstrate new types of quantum devices on the level of two-particle interaction.

I will present several recent results in systems of dipolar excitons and polaritons. These include experimental evidence for the dynamical formation of a robust dark dense liquid phase of dipolar excitons in a bilayer system [2],

and the observation of a formation of an attractive di-polaron-like many-body correlated state [3]. This effect, which is due to the anisotropic nature of the dipole-dipole interaction, takes place in a new structure design allowing vertical coupling of dipolar exciton fluids, and is a first step towards realizing an exciton dipolar pair superfluid [4], an elusive and exotic collective phase.

Finally, I will introduce recent experiments with ‘flying’ electrically polarized dipolar-polaritons (‘dipolaritons’) in optical waveguides. These are electrically tunable exciton-photon super-position states that effectively act as “interacting photons” [5]. I will present a demonstration of a dipolar mirror and a dipolar transistor for such hybrid photons, a result promising for future implementations of a dipolar blockade and quantum circuitry of light.  

Bibliography:

[1] See e.g., Fabian Böttcher, Jan-Niklas Schmidt, Matthias Wenzel, Jens Hertkorn, Mingyang Guo, Tim Langen, and Tilman Pfau “Transient Supersolid Properties in an Array of Dipolar Quantum Droplets” Phys. Rev. X 9, 011051 (2019), Tanzi, L., Roccuzzo, S.M., Lucioni, E. et al. “Supersolid symmetry breaking from compressional oscillations in a dipolar quantum gas” Nature 574, 382–385 (2019)

[2] Yotam Mazuz-Harpaz, Kobi Cohen, Michael Leveson, Ken West, Loren Pfeiffer, Maxim Khodas, and Ronen Rapaport "Dynamical formation of a strongly correlated dark condensate of dipolar excitons", Proc. Nat. Acad. Sci. 116 (37) 18328; (2019)

[3] Colin Hubert, Yifat Baruchi, Yotam Mazuz-Harpaz, Kobi Cohen, Klaus Biermann, Mikhail Lemeshko, Ken West, Loren Pfeiffer, Ronen Rapaport, and Paulo Santos, "Attractive dipolar coupling between stacked exciton fluids", Phys. Rev. X 9, 021026 (2019)

[4] Michal Zimmerman, Ronen Rapaport, Snir Gazit “Collective inter-layer pairing and pair-superfluidity
in vertically-stacked layers of dipolar excitons”, arXiv:2202.11754 (2022)
[5] Itamar Rosenberg, Dror Liran, Yotam Mazuz Harpaz, Ken West, Loren N. Pfeiffer, Ronen Rapaport “Strongly interacting dipolar polaritons”, Science Advances, 4, eaat8880 (2018)

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