Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 29: Quantenkoh
ärenz und Quanteninformationssysteme II

TT 29.13: Talk

Thursday, March 11, 2004, 17:45–18:00, H19

Quantum versus classical temperature profiles — •Michael Hartmann^1,2, Günter Mahler² und Ortwin Hess³ — ¹Institut für Technische Physik, DLR Stuttgart, Pfaffenwaldring 38 - 40, D-70569 Stuttgart — ²Institut für Theoretische Physik I, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart — ³School of Electronics & Physical Sciences, University of Surrey, GU2 7XH, UK

We consider a quantum system consisting of a regular chain of elementary subsystems with nearest neighbour interactions and form groups of N subsystems each. Assuming that the total system is in a canonical state ρ = exp(H / k T) / Z with temperature T we analyse under what condition the state may be decomposed into a product of canonical density matrices of the subgroups,
ρ′ = ∏_i exp(H_i / k T) / Z_i, with the same temperature T. We then compare the classical and the quantum regime and apply our analysis to a harmonic chain as an example.