Decoherence and thermalization dynamics of a quantum oscillator

Abstract

We introduce the quantitative measures characterizing the rates of decoherence and thermalization of quantum systems. We study the time evolution of these measures in the case of a quantum harmonic oscillator whose relaxation is described in the framework of the standard master equation, for various initial states (coherent, `cat', squeezed and number). We establish the conditions under which the true decoherence measure can be approximated by the linear entropy $1-Tr{\hat{\rho }}^2$. We show that at low temperatures and for highly excited initial states the decoherence process consists of three distinct stages with quite different time scales. In particular, the `cat' states preserve 50% of the initial coherence for a long time interval which increases logarithmically with increase of the initial energy.

24 pages, LaTex, 8 ps figures, accepted for publication in J. Opt. B

References in corpus (4)

• Open quantum systems
• Energy-Sensitive and "Classical-like" Distances Between Quantum States
• Purity and decoherence in the theory of a damped harmonic oscillator
• Uncertainty, entropy and decoherence of the damped harmonic oscillator in the Lindblad theory of open quantum systems

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