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DY: Fachverband Dynamik und Statistische Physik
DY 8: Quantum dynamics, decoherence and quantum information
DY 8.4: Talk
Monday, March 26, 2007, 17:00–17:15, H2
Quantum Thermodynamic Machines and their Limits — •Markus Henrich, Mathias Michel, and Günter Mahler — 1. Institut für Theoretische Physik, Universität Stuttgart, Deutschland
How small can a system be to act as a thermodynamic machine? We show that a 3-spin system driven with finite speed and interfaced between two split baths constitutes such a minimal model. The spins are arranged in a chain with nearest-neighbor interaction and different local Zeeman-splittings. The working spin in the middle is driven in σZ-direction and exercises Carnot cycles the area of which defines the exchanged work [1].
We compare the numerical results of this machine with an ideal one which can be solved analytically. It can be shown under which conditions the Carnot efficiency should be reached and that a critical temperature exists where the machine begins acting as a heat pump [2]. The influence of leakage heat currents on the efficiency are investigated additionally.
[1] M. J. Henrich et al, "’Small quantum networks operating as quantum thermodynamic machines"’, cond-mat/0604202
[2] T. D. Kieu, "’Quantum heat engines, the second law and Maxwell’s daemon"’, Eur. Phys. J. D 39, 115-128 (2006)