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Quantum Field Theory and Many Body Physics 2020

Class will be online only!

For participation, please register in Campus Management ahead of April 20 - including your email address! Otherwise, I have no way of inviting you to the meetings and you will not be able to access the online material.

Lectures are available as videos and lecture notes, and will be assigned on a weekly basis. Online meetings will be held Mo 10-12 and Th 10-12 (starting April 20) for question-and-answer and discussion sessions.

In addition, there will be online tutorials Fr 10-12 (starting April 24).

Problem sets will be made available on Thursdays and have to be turned in electronically by the following Thursday at 10am at the latest.


1) The grade will be based on a 15min presentation on an (assigned) paper followed by 15min of questions on the paper and other class content (all online). (You can opt out of this and insist on a written exam. However, this would have to be postponed until better times.)

2) The exams will take place on Mo August 3 and Tu August 4. The topics for the presentation will be distributed among the participants by random number generator during the lecture on July 13.  

3) Please communicate by email by July 6 if you intend to participate in the exam. 

General Information

Problem sets

Set 1 (due April 30)                                 Solution
Set 2 (problem 1: due ahead of every lecture; problem 2-4: due May 7)           Solution
Set 3 (due May 14; video summaries ahead of every lecture)                           Solution
Set 4 (due May 21; video summaries ahead of every lecture)                           Solution
Set 5 (due May 28; video summaries ahead of every lecture)                           Solution
Set 6 (due June 4; video summaries ahead of every lecture)                            Solution
Set 7 (due June 11; video summaries ahead of every lecture)                          Solution
Set 8 (due June 18; video summaries ahead of every lecture)                         Solution
Set 9 (due June 25; video summaries ahead of every lecture)                         Solution
Set 10 (due July 2; video summaries ahead of every lecture)                          Solution
Set 11 (due July 9; video summaries ahead of every lecture)                          Solution

Video lectures and lecture notes

Chapter 1: Landau Theory of Phase Transitions                     (bonus material)           

Chapter 2: Quantum Phase Transitions                                  

Chapter 3: Free bosonic fields: harmonic chain  

Chapter 4: Path integrals

Chapter 5: Green functions and linear response

  • Kubo formula                                                                      Th May 14
  • Lehmann representation I                                                   Mo May 18
  • Lehmann representation II                                                  Mo May 18
  • Linear response and dissipation                                         Mo May 18

Chapter 6: Boson functional integral

Chapter 7: Interacting Bose systems

Chapter 8: Boson superfluidity

  • Action and gauge invariance                                               Mo Jun 8
  • Electromagnetic response                                                   Mo Jun 8
  • Anderson-Higgs mechanism                                               Mo Jun 8                    

Chapter 9: Bosons at finite temperatures

  • Dimensional analysis                                                           Th Jun 11
  • Bosons at finite temperatures                                              Th Jun 11
  • Vortices and Kosterlitz-Thouless transition                          Th Jun 11
  • Coulomb gas model                                                             Mo Jun 15
  • Real space renormalization                                                 Mo Jun 15
  • RG flow                                                                                Mo Jun 15

Chapter 10: Fermion functional integrals

Chapter 11: Random-phase approximation

Chapter 12: BCS theory

  • Effective action                                                                    Th Jul 2
  • Gap equation                                                                       Th Jul 2
  • Condensation energy                                                          Th Jul 2
  • Ginzburg-Landau theory I                                                    Mo Jul 6
  • Ginzburg-Landau theory II                                                   Mo Jul 6

Chapter 13: Feynman diagrams: Thermodynamic potential

Chapter 14: Feynman diagrams: Green functions