# Tilman Enss | Teaching

as of 29 June 2016

## News

## 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

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

#### 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

Date | Problem set | Date 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 | |

29.06.2016 | Set 11: Bogoliubov, condensation energy, Hubbard-Stratonovich | 08.07.2016 |

#### 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

#### Further material

- Anderson, More is different, Science
**177**, 393 (1972) - Sigrist, Lecture notes on Solid State Theory
- for a crash course in statistical physics, see e.g. Fetter/Walecka, ch. 2

#### 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.