PHYS-EV0001 - Quantum field theory in condensed matter physics, Lecture, 9.1.2023-6.4.2023
This course space end date is set to 06.04.2023 Search Courses: PHYS-EV0001
Week 8 prelecture assignment
Completion requirements
Due: Monday, 6 March 2023, 2:15 PM
This week we will be studying vacuum state, although in condensed matter physics the 'vacuum' state is actually redefined as the many-body ground state of a system.
On Monday we will start by adding the last ingredient missing from our definition of the many-body Green's function: normalization. Normalizing the Green's function by the ground state wavefunctions norm cancels all the disconnected diagrams that we have so far neglected (and can thus keep neglecting). On Monday you will also repeat Hans Bethe's calculation for the Lamb's shift, mentioned in the video.
Bethe's calculation was the first application of 'renormalization', and on Wednesday we will have a brief look at another case of renormalization: delta-function interaction that we already met in the scattering calculation on week 4.
And on Thursday we will study Casimir effect.
Please watch the following PBS Space time video on nature of
vacuum:
At
the end of the video, Matt discusses Casimir effect. Are you familiar
with the effect? A closely related effect is van
der Waals interaction. Please tell shortly what it is. Any questions or comments?