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DY: Dynamik und Statistische Physik

DY 22: Quantum Dynamics II

DY 22.5: Vortrag

Dienstag, 28. März 2006, 12:00–12:15, H\"UL 186

Normal transport behaviour in one-dimensional chaotic quantum systems — •Robin Steinigeweg and Jochen Gemmer — Physics Department, University of Osnabrück, Barbarastr. 7, 49069 Osnabrück, Germany

We investigate the transport behaviour of several one-dimensional (1D) quantum systems neither modelling heat baths nor using standard methods as the Kubo formula for heat conduction. Instead we numerically solve the corresponding time-dependent Schrödinger equation for various initial states and model parameters. It turns out that within the parameter range where normal transport occurs, that is, Fourier’s law applies the nearest neighbour level spacing distribution (NNLSD), P(s), can be well described by a Wigner distribution. Amongst others we also investigate a spin system, namely a s = 1/2 Heisenberg chain in an external magnetic field B. Since this integrable system has a Poisson-like distribution P(s) and does not show normal transport, we allow (small) local variations B_µ from the mean field B. As a consequence the distribution P(s) becomes Wigner-like and normal transport occurs. This result reaffirms the assumption that normal transport behavior of 1D quantum systems is associated with a Wigner-like NNLSD.