Quantum thermodynamics under observation: The influence of periodic quantum measurements
Institut für Theoretische Physik 1, Universität Stuttgart - Pfaffenwaldring 57, D-70550 Stuttgart, Germany, EU
Corresponding author: firstname.lastname@example.org
Accepted: 7 June 2010
Within a quantum-thermodynamical approach a single subsystem can be shown to relax to a thermal state if appropriately embedded in a quantum environment. This picture appears to be at variance with the foundations of statistical mechanics, according to which thermal properties emerge either as a long-time or ensemble average. Here we argue that periodic measurements on the environment may establish the missing link: we consider a two-level system (TLS) coupled to an environment consisting of many spins, the magnetization of which is measured periodically. These measurements destroy system-environment correlations and influence the state of the TLS due to so-called co-jumps, which lead to quasi-classical trajectories for the TLS. We derive an analytical solution for the ensemble-averaged attractor state reached after many measurements. Reinterpreting the setup as an indirect measurement process for the TLS also sheds new light on the properties of such periodic indirect measurements.
PACS: 05.70.Ln – Nonequilibrium and irreversible thermodynamics / 05.30.-d – Quantum statistical mechanics / 03.65.Xp – Tunneling, traversal time, quantum Zeno dynamics
© EPLA, 2010