Europhys. Lett, 47 (3), pp. 279-284 (1999)
Selection of squeezed states via decoherence
Department of Physics, University of Illinois at Urbana-Champaign
1110 W. Green St., Urbana, IL 61801, USA
(received 25 January 1999; accepted in final form 3 June 1999)
PACS. 03.65Bz - Foundations, theory of measurement,
miscellaneous theories (including Aharonov-Bohm effect, Bell inequalities, Berry's phase).
PACS. 05.30 - Quantum statistical mechanics.
PACS. 05.40 - Fluctuation phenomena, random processes, noise, and Brownian motion.
In the framework of Lindblad theory for open quantum systems, we calculate the entropy of a damped quantum harmonic oscillator which is initially in a quasi-free state. The maximally predictable states are identified as those states producing the minimum entropy increase after a long enough time. In general, the states with a squeezing parameter depending on the environment's diffusion coefficients and friction constant are singled out, but if the friction constant is much smaller than the oscillator's frequency, coherent states (or thermalized coherent states) are obtained as the preferred classical states.
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