Superconductivity and Low Temperature Physics 2

This module provides a detailed discussion of the fascinating properties of quantum fluids, mesoscopic solid state systems (nanostructures) as well as experimental low temperature techniques. The following specific topics will be addressed:

• Bose-Einstein condensation
• superfluid Helium-3 and Helium-4
• Quantum interference effects in mesoscopic metallic systems (weak localization, universal conductance fluctuations, etc.)
• Coulomb blockade and single electron transistors
• generation of low temperatures
• measurement of low temperatures

After successful completion of the module the students are able to:

• to identify the fundamental differences between classical and quantum liquids.
• to describe the transition from a classical to a quantum liquid by reducing the temperature.
• to explain the relevance of quantum statistics (bosons vs. fermions) for the general behavior of quantum liquids.
• to derive the expression of the Bose-Einstein condensation temperature. 
• to list and explain the basic properties of superfluid He-4 and He-3.
• to list and explain the characteristic length and time scales playing an important role for charge transport in mesoscopic conductors as well as to apply them for the description of charge transport phenomena.
• to describe the impact of quantum interference effects in the charge transport in mesoscopic systems and to explain phenomena such as universal conductance fluctuations and weak localization.
• to list the most relevant methods for the generation of low temperatures as well as to describe and explain their physical foundations. 

Basic knowledge on condensed matter physics and quantum mechanics.

In the thematically structured lecture the learning content is presented by blackboard work, beamer presentation). With cross-references between different topics the universal concepts in physics are shown. The students are involved in scientific discussions to stimulate their analytic and physics-related intellectual power.

In the exercise groups the learning content is deepened and exercised using problem examples and calculations. Thus the students are able to explain and apply the learned physics knowledge independently.

Lecture Notes, exercise sheets, supplementary literature, PowerPoint slides, movies, etc..

• Handouts
• Enns/Hunklinger: Low Temperature Physics
• Heinzel: Mesoscopic Electronics in Solid State Nanostructures
• Pobell: Matter and Methods at Low Temperatures
• Kent: Experimental Low Temperature Physics

There will be an oral exam of 30 minutes duration. Therein the achievement of the competencies given in section learning outcome is tested exemplarily at least to the given cognition level using comprehension questions and sample calculations.

For example an assignment in the exam might be:

• Describe the fundamental differences between classical and quantum liquids
• Discuss the transition from a classical to a quantum liquid on lowering the temperature
• Explain the relevance of quantum statistics (bosons vs. fermions) for the behavior of quantum liquids
• Provide an estimate of the Bose-Einstaein condensation temperature
• Explain the basic properties of superfluid He-4 and He-3. What are the key differences?
• Describe the characteristic length and time scales relevant for the conduction properties of mesoscopic conductors. How do the change with temperature?
• What is the impact of quantum interference effects on the charge transport in mesoscopic conductors?
• What are universal conductance fluctuations, what is weak localization? How can we measure these phenomena?
• What are the most important methods for the generation and measurement of low temperature? What are the physical phenomena they are based on?

Participation in the exercise classes is strongly recommended since the exercises prepare for the problems of the exam and rehearse the specific competencies.