Regensburg 2010 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 6: Poster Session I

DY 6.47: Poster

Monday, March 22, 2010, 16:00–18:00, Poster B2

Quantum Thermodynamics and periodic quantum measurements — •Thomas Jahnke and Günter Mahler — Universität Stuttgart, 1. Institut für Theoretische Physik, Pfaffenwaldring 57, 70550 Stuttgart

It is known from Quantum Thermodynamics [1] that the Schrödinger dynamics of a closed bi-partite quantum system typically enforces a stationary thermalized state on the smaller subsystem. This seems to be at variance with the common picture of classical statistics, according to which the individual system continues to move through its allowed space of microstates such that the respective thermal state is established as the infinite time average only.

Here we argue that the link between these two descriptions can be found in terms of observations from the outside: Projective measurements of the environment influence the system dynamics due to “co-jumps” and destruction of system-environment correlations.

Concretely, we investigate a two-level system (TLS) coupled to an environment consisting of many spins, the magnetization of which is measured periodically. Considering the ensemble average, we derive an analytical solution for the dynamical attractor state reached after many measurements.