Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 83: Correlated Electrons: Nonequilibrium Quantum Many-Body Systems I

TT 83.5: Talk

Thursday, April 3, 2014, 10:45–11:00, HSZ 03

Excited states above a non-equilibrium steady state (NESS) and approach to NESS — •Mariya Medvedyeva and Stefan Kehrein — Goettingen University

The simplest way to address the evolution of an open quantum system is the Lindblad equation, which describes a quantum system coupled to a classical environment. In the long-time time limit the system reaches a non-equilibrium steady state (NESS). The spectrum of the Liouvillian operator from the Lindblad equation determines the excited states with respect to the NESS. In general, the spectrum consists of complex numbers, whose real parts determine the relaxation speed while the imaginary parts lead to oscillations. The approach of a generic initial state to equilibrium is determined by the longest-living excited states which do not oscillate. If the density of such states shows a power law behavoir close to zero, then the approach to NESS also follows a power-law rather than an exponential behavior. We demonstrate this statement for the example of non-interacting fermions coupled to a Markovian bath, where the solution can be found exactly (up to numerical matrix diagonalization).