Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.53: Poster

Mittwoch, 24. März 2010, 14:00–18:00, Poster D1

Non-equilibrium steady state in a periodically driven Kondo model — Markus Heyl and •Stefan Kehrein — Ludwig-Maximilians-Universität, Theresienstrasse 37, 80333 München

We investigate the Kondo model with time-dependent couplings that are periodically switched on and off. On the Toulouse line we solve the problem exactly by using bosonization and refermionization that are also suitable for the Kondo model out of equilibrium [1]. We derive exact analytical results for the spin dynamics in the steady state that builds up after an infinite number of switching periods. Remarkably, the algebraic long time behavior of the spin-spin correlation function remains completely unaffected by the driving. In the limit of slow driving the dynamics becomes equivalent to that of a single interaction quench. In the limit of fast driving one can show that the steady state cannot be described by some effective equilibrium Hamiltonian since a naive implementation of the Trotter formula gives wrong results. As a consequence, the steady state in the limit of fast switching serves as an example for the emergence of new quantum states not accessible in equilibrium.

[1] D. Lobaskin and S. Kehrein, Phys. Rev. B 71, 193303 (2005).