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TT: Fachverband Tiefe Temperaturen

TT 38: CE: Quantum-Critical Phenomena 2

TT 38.3: Vortrag

Freitag, 26. März 2010, 10:45–11:00, H18

Quantum aging in a sub-Ohmic heat bath — •Peter Nalbach and Michael Thorwart — FRIAS, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg i.Br.

We show that the low-frequency modes of a sub-Ohmic bosonic heat bath generate a dynamical asymmetry for an intrinsically symmetric quantum spin−1/2, which induces a slowly-decaying quasiequilibrium for the spin resembling a generic “aging” dynamics. The symmetry breaking is related to the dynamic crossover between coherent and overdamped relaxation of the spin polarization. For nonequilibrium initial conditions, we identify a so far unknown phase, characterized by damped coherent oscillations in the localized phase. A zero-temperature phase diagram is sketched.