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 10 Prelecture assignment
On week 10 we will go a bit deeper in to the gauge symmetry that was briefly mentioned on week 5 in connection with the Thomson and Rayleigh scattering. The coupling of charged particles with the electromagnetic field is done by the minimal coupling with the scalar and vector potentials. However, the physical electric and magnetic fields do not uniquely determine the scalar and vector potentials, which means that we are allowed to make a choice of a gauge. The freedom to choose different gauges, without affecting the physical observable quantities, implies a (continuous) symmetry. And according to the Noether's theorem, there is an associated conserved current.
As a warm up to the topic, please watch the PBS Space Time video on standard model:
We are not going to discuss the full U(1)xSU(2)xSU(3) model, since in condensed matter physics we do not need to worry about weak and strong interactions, but the U(1) phase symmetry is important for understanding condensates, superfluids and even ferromagnetism. Magnetism has probably not been taught in many courses in Aalto. Have you been studying ferromagnetism or other forms of magnetic materials in some courses? What about superconductivity? Do you have any questions?