Volume 83, Number 3, August 2008
Article Number 30008
Number of page(s) 5
Section General
Published online 18 July 2008
EPL, 83 (2008) 30008
DOI: 10.1209/0295-5075/83/30008

Local effective dynamics of quantum systems: A generalized approach to work and heat

H. Weimer, M. J. Henrich, F. Rempp, H. Schröder and G. Mahler

Institute of Theoretical Physics I, University of Stuttgart - Pfaffenwaldring 57, 70550 Stuttgart, Germany, EU

received 13 November 2007; accepted in final form 13 June 2008; published August 2008
published online 18 July 2008

By computing the local energy expectation values with respect to some local measurement basis we show that for any quantum system there are two fundamentally different contributions: changes in energy that do not alter the local von Neumann entropy and changes that do. We identify the former as work and the latter as heat. Since our derivation makes no assumptions on the system Hamiltonian or its state, the result is valid even for states arbitrarily far from equilibrium. Examples are discussed ranging from the classical limit to purely quantum-mechanical scenarios, i.e. where the Hamiltonian and the density operator do not commute.

05.30.-d - Quantum statistical mechanics.
03.65.-w - Quantum mechanics.
05.70.Ln - Nonequilibrium and irreversible thermodynamics.

© EPLA 2008