Welcome to FIM670 Q3 Superconducticity and Low Temperature Physics

Previous knowledge

A basic course in quantum mechanics (i.e. FUF040), and a basic course in solid state physics/electronics (i.e. FFY011).

Aim

Physical phenomena are often studied at low temperature, particularly within condensed matter physics. Coherence effects become dominating. The course contents are concentrated to a few sub-fields: 1. studies of superconductors (about half the time), both an understanding of superconductivity starting from microscopic properties and of macroscopic quantum effects, particularly the Josephson effects; 2. properties of superfluid helium and Bose-Einstein condensates, i.e. of macroscopic quantum fluids; 3. mesoscopic effects, for example single electronics 4. low temperature techniques, i.e. a summary of different cooling methods, thermal properties of materials, thermometry, etc. One purpose is to meet models that can be applied to other fields of Physics. The course is suitable for those that want to continue doing research in Physics.

Learning outcome (after completion of this course, the student should be able to)

Explain the basic properties of both high Tc and low Tc superconductors.
Apply Londons equations to superconductors to explain their electromagnetic properties.
Describe thermodynamic properties of superconductors
with the help of Ginzburg Landau theory describe different lengthscales such as the penetration depth and the coherence length, and explain the differences between type I and type II superconductors.
Account for the basic ideas of the BCS theory, like Cooper-pairing, energy gap and the density of states for exitations.
Describe the phase diagrams for both helium-3 and helium-4.
Describe how Bose-Einstein condensation comes about.
Describe superfluid phenomena such as, rollin film, the fountain effect and second sound.
Describe different cooling methods which are used both above and below 1 Kelvin.
Explain physical properties of different materials at low temperature.

Contents

The course may be considered as an application of courses in quantum physics, solid state physics, electrodynamics and thermodynamics.
The course has three parts:

SUPERCONDUCTIVITY
Basic properties of superconductors, thermodynamics, superconductors in magnetic fields
The London equations, electromagnetic properties, penetration depth
Ginzburg-Landau theory, coherence length, type I and type II superconductors
BCS theory, second quantization, Cooper-pairing, energy gap
Tunneling, Josephson effects and SIS tunneling
High Tc superconductors, structure, d-wave symmetry, phase diagram,
Overview of applications, squids, microwave devices, power applications

SUPERFLUIDITY
Properties of liquid helium-4, the phase diagram, superfluidity
Superfluid phenomena, rollin film, fountain effect, second sound
Exitations and vortecies in superfluids
Properties of liquid helium-3, the phase diagra, superfluidity
Symmetry properties of superfluid helium-3

CRYOGENICS
Themal and electrical properties for different materials at low temperature
Cooling methods above 1K, Joule-Tomphson, Gifford-McMahon, evaporation cooling
Liquefication of helium
Cooling methods below 1K, dilution refrigeration, adiabatic demagnetisation, Pomerantchuck cooling

Organisation

The course embraces lectures (about 30 hours), two laborations (Josephson effect, and superfluid helium)and home exercises.

Literatur

J.R. Waldram: Superconductivity of metals and cuprates
(Institute of Physics Publ., Bristol, 1996, pbk)
Lecture notes.

Examination

The course ends with a written exam. There is a laboratory part that must be taken.