Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 26: Quantum Dynamics, Decoherence and Quantum Information (jointly with DY)

TT 26.10: Talk

Monday, March 16, 2015, 17:30–17:45, BH-N 334

Non-equilibrium quantum dynamics of Gaussian states in open harmonic chains — •Thomas Motz, Jürgen T. Stockburger, and Joachim Ankerhold — Institute for complex quantum systems, Ulm University, Albert-Einstein-Allee 11, D-89069 Ulm, Germany

Strong driving in open quantum systems can reveal counterintuitive effects such as the dynamical creation of negative entropy changes [1] and entanglement between two Gaussian modes in a common reservoir [2]. The effect that dissipation and strong driving in combination can lead to specific quantum characteristics like entanglement and offers much potential for quantum information processing and the studies of mesoscopic thermodynamics. A rich tool to study dynamic effects in open systems proved to be the stochastic Liouville-von Neumann equation [3]. We avoid the stochastic sampling in our approach where the dynamics of the covariance matrix in a few-body system is directly described by a deterministic equation of motion. We apply this approach to a bipartite asymmetric system where entanglement generation and its sensitivity to the asymmetry is studied. Since the memory requirements for Gaussian states grow only quadratically with system size, our approach is also targeted at more complex settings like multiple coupled modes in a common or several separated reservoirs. Our equations of motion allow optimal control theory to be applied with ease.

[1] R. Schmidt et al., PRL 107, 130404 (2011).

[2] R. Schmidt et al., PRA 88, 052321 (2013).

[3] J. T. Stockburger and H. Grabert, PRL 88, 170407 (2002).