# Tilman Enss | Teaching

as of 9 Sept 2016

## News

2016-09-08: The retry exam will take place on Wednesday October 12th, 11.15-12.45h in Philosophenweg 19 (seminar room).

## Condensed Matter Theory (MVTheo2)

#### Summer term 2016

This course introduces the concepts and methods of modern condensed matter theory. In the first part, Green's functions and the diagrammatic technique are used to discuss metals, Fermi liquids and superconductors. The second part covers several advanced topics such as Bose-Einstein condensation, quantum phase transitions, and the Kondo effect. The exercises also show how to compute experimental observables.

Description in the course handbook (page 67)

#### Contents

1. Introduction
2. Fermions, bosons, and second quantization
3. Electrons in periodic crystals, band structure
4. Green's functions and perturbation theory
5. Metals: Jellium model, charge excitations, and phonons
6. BCS theory of superconductivity
7. Bose-Einstein condensation, superfluidity and symmetry breaking
8. Magnetism and quantum phase transitions

Lecture notes (for participants)

#### Dates and Location

Lecture Monday 11.15-13.00h, Philosophenweg 12, kHS [LSF]
and Wednesday 11.15-13.00h, Philosophenweg 12, kHS.

Exercise (Dr. Valentin Kasper) Friday 09.15-11.00h, Phil 12 / kHS.
Please register for the course at this URL for notifications and/or for taking part in the exam; you may unregister yourself before July 18.

#### Problem sets

DateProblem setDate due (tutorial)Solution
20.04.2016 Set 1: Ideal gas, correlations, operator algebra 29.04.2016 Solution 1
27.04.2016 Set 2: Kronig-Penney, tight binding model 06.05.2016 Solution 2
04.05.2016 Set 3: Graphene, Wannier functions 13.05.2016 Solution 3
11.05.2016 Set 4: Linear response, diffusion, Kramers-Kronig, quasiparticle 20.05.2016 Solution 4
18.05.2016 Set 5: Berry phase, Matsubara sum, Interaction 27.05.2016 Solution 5
25.05.2016 Set 6: Grassmann, perturbations, Landau levels 03.06.2016 Solution 6
01.06.2016 Set 7: Hartree-Fock, potential scattering, Gauss integral 10.06.2016 Solution 7
08.06.2016 Set 8: Polarized gas, random-phase approximation 17.06.2016 Solution 8
15.06.2016 Set 9: Plasma oscillation, Fröhlich, variational HF 24.06.2016 Solution 9
22.06.2016 Set 10: Linear chain, Einstein phonons, Cooper pairs 01.07.2016 Solution 10
29.06.2016 Set 11: Bogoliubov, condensation energy, Hubbard-Stratonovich 08.07.2016 Solution 11
06.07.2016 Set 12: Gap equation, spin susceptibility, 2D BEC 15.07.2016 Solution 12

#### Prerequisites

• Quantum Mechanics (PTP4)
• Theoretical Statistical Physics (MKTP1) — recommended

#### Literature

• Ashcroft and Mermin, Solid State Physics
• Altland and Simons, Condensed Matter Field Theory
• Fetter and Walecka, Quantum Theory of Many-Particle Systems
• Negele and Orland, Quantum Many-Particle Systems
• Tinkham, Introduction to Superconductivity
• Xiao-Gang Wen, Quantum Field Theory of Many-Body Systems

#### Exam

The written exam will be held on Monday, 25 July 2016, from 11:15-12:45h. The exam will be graded; those who pass will get 8 credit points. In order to participate in the exam you will need to register for the course at this URL; you may unregister yourself before July 18. The retry exam for those who did not pass the first one will take place on Wednesday, 12 October 2016, from 11:15-12:45h in Philosophenweg 19 (seminar room).

Teaching in previous semesters