Eur. Phys. J. B 53, 517-528 (2006)
https://doi.org/10.1140/epjb/e2006-00407-3

Finite quantum environments as thermostats: an analysis based on the Hilbert space average method

¹ Physics Department, Universität Osnabrück, Barbarastr. 7, 49069 Osnabrück, Germany
² Institut für Theoretische Physik I, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany

Corresponding author: ^a jgemmer@uos.de

Received: 13 September 2006
Published online: 10 November 2006

Abstract

We consider discrete quantum systems coupled to finite environments which may possibly consist of only one particle in contrast to the standard baths which usually consist of continua of oscillators, spins, etc. We find that such finite environments may, nevertheless, act as thermostats, i.e., equilibrate the system though not necessarily in the way predicted by standard open system techniques. Thus, we apply a novel technique called the Hilbert space Average Method (HAM) and verify its results numerically.