Linear response for gapped fermionic systems based on non-equilibrium almost steady states
Spectral Methods in Mathematical Physics
21 February 14:00 - 15:00
Stefan Teufel - Universität Tübingen
I will present a justification of linear (and higher order) response formulas for gapped systems of interacting lattice fermions based on an extension of the adiabatic theorem to situations where a time-dependent perturbation closes the gap, but leaves intact a local gap structure. According to the standard version of the adiabatic theorem, when the perturbation is switched on adiabatically and as long as the gap does not close, the initial ground state evolves into the ground state of the perturbed operator.
The new adiabatic theorem states that for perturbations that are either slowly varying potentials or small quasi-local operators, once the perturbation closes the gap, the adiabatic evolution follows non-equilibrium almost-stationary states (NEASS) that can be constructed explicitly.
University of Zurich, UZH