Physics (Internal)

Transient Orthogonality Catastrophe in a Time Dependent Nonequilibrium Environment

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: We study the response of highly-excited time dependent quantum many-body states to sudden local perturbations, a sort of orthogonality catastrophe problem in transient non-equilibrium environments. As a key quantity we look at the overlap between time dependent wave-functions in presence or absence of the local potential, that we write as a novel two-time correlation function generalizing the standard Loschmidt Echo. We present explicit calculations for one dimensional fermions excited by a sudden change of the interaction and perturbed by the switching on of a local static potential. Our results reveal an intermediate time regime where the two-time Loschmidt Echo features power law decay and aging. On longer time scales the interplay between non equilibrium excitation of bulk modes and local nonlinearity generates an exponential decay in time of the Echo, reminiscent of an effective thermal behavior. We discuss possible experimental signatures of this quench-induced decoherence effect both in transport and in dynamics using non-equilibrium Ramsey interferometry schemes.

Refs: M. Schiro', A. Mitra Phys. Rev. Lett. 112, 246401 (2014) M. Schiro', A. Mitra, arXiv:1502.06538