פרופ' בוריס שפירא- פיסיקה של טמפרטורות נמוכות 86-899

א.      מטרות הקורס:

 

Low Temperature physics is a branch of physics dealing with physical properties of matter at temperatures such that thermal fluctuations are greatly reduced and effects of interactions at the quantum-mechanical level can be observed. As the temperature is lowered, order sets in and quantum-mechanical phenomena can be observed on a macroscopic scale. Some of the most interesting manifestations of low temperatures have been investigated in the temperature range from 4 K down to less than a nanokelvin above absolute zero.  Many practical applications have emerged, including the use of superconductivity for large magnets, ultra fast electronics for computers, and low-noise and high-sensitivity instrumentation. This type of instrumentation has opened new areas of research in bio-physics, and in fundamental problems such as the search for magnetic monopoles, gravity waves, and quarks.

     בתוכן הקורס:

 

I.                  CRYOGENICS
1. Thermal and electrical properties of solids at low temperature.
2. Cooling methods above 1K, Joule-Thompson, Gifford-McMahon, evaporation cooling. Liquefaction of helium. Cooling methods below 1K, dilution refrigeration, adiabatic demagnetization, Pomerantchuck cooling. 3. Laser cooling.
 

II.               SUPERCONDUCTIVITY
1. Basic properties of superconductors, thermodynamics, superconductors in magnetic fields.
2. The London equations, electromagnetic properties, penetration depth
Ginzburg-Landau theory, coherence length, type I and type II superconductors, Second quantization, Electron-electron attraction, Cooper-pairing, BCS theory, Microscopic tunneling theory. Critical current, Josephson effects and SIS tunneling.
3. High superconductors, structure, d-wave symmetry, phase diagram, pseudogap regime. Pi Josephson junction. Spontaneous vortices in three-corner junctions.
4. Overview of applications, squids, microwave devices, power applications.

III.      SUPERFLUIDITY

 1. Properties of liquid helium-4, the phase diagram.

     Superfluid phenomena, rolling film, fountain effect.

 2. Two-liquids hydrodynamics. First and second sounds.
     Phonons and rotons. Ripplons.       
 3. Gross-Pitaevsky equation. Excitations and vortices in superfluids.
     Properties of liquid helium-3, the phase diagram, superfluidity,

 4. Symmetry properties of superfluid helium-3. BW and AM states.

     BEC in interacting systems. Excitations and gap in superfluid He-3.

 5. Bose and Fermi alkali gases: the BEC-BCS crossover.

     Feshbuch Resonance.

 

ג. חובות הקורס:

 

     דרישות קדם: מצב מוצק, מכניקה קוונטית ופיסיקה סטטיסטית

 

 חובות: נוכחות והגשת עבודה

 

 מרכיבי הציון הסופי: 80%- עבודת בית, 20%- נוכחות

 

ד. ביבליוגרפיה:

 

1. A. J. Leggett    Quantum Liquids, Oxford Press, 2006.

2. J. B. Ketterson and S.N. Song, Superconductivity, Kambridge Press, 1999.

3. G. Burns   High Temperature Superconductors, Academic Press, 1992.

4. J.R. Waldram: Superconductivity of metals and cuprates
(Institute of Physics Publ., Bristol, 1996);

5. L.D. Landau, E.M. Lifshitz, Statistical Physics, v.9  Pergamon Press, 1980.