Diagrammatic many-body theory for light-driven materials (IMPRS UFAST focus course)

Abstract:

Non-equilibrium Green’s functions (NEGF) provide a versatile framework to describe driven quantum many-particle systems, from photo-induced phase transitions in correlated materials to dynamically stabilized states in synthetic quantum matter. The formalism provides both the basis for perturbative approaches (e.g., the GW formalism for electronic structure, time-dependent Migdal-Eliashberg theory for non-equilibrium superconductors, real-time RPA approaches to describe the charge density wave instabilities, etc.), and non-perturbative methods such as dynamical mean-field theory (DMFT), which can describe electrons in the vicinity of the Mott transition (the magic spot for emergent complex phases of matter).

Theoretical concepts:

Brief summary of important models (Hubbard model, etc.)
Light-matter interaction in solids
Green’s functions, spectral functions, and self-energies
Theory for time-resolved spectroscopies (mainly trARPES)
The Keldysh formalism
A practitioners guide to Feynman diagrams
Numerical treatment
Coherent state path integrals for Fermions
Dynamical mean field theory in and out of equilibrium

Physics examples:
Floquet-Bloch states
Dynamical phase transitions, non-thermal criticality
Photo-doped Mott-insulators
Hand’s on examples using NESSi

29th November – 1st & 6th - 8th December 2023

09:30h - 12:00h

Poster (pdf)