699 research outputs found
Uncertainty, entropy and decoherence of the damped harmonic oscillator in the Lindblad theory of open quantum systems
In the framework of the Lindblad theory for open quantum systems, expressions
for the density operator, von Neumann entropy and effective temperature of the
damped harmonic oscillator are obtained. The entropy for a state characterized
by a Wigner distribution function which is Gaussian in form is found to depend
only on the variance of the distribution function. We give a series of
inequalities, relating uncertainty to von Neumann entropy and linear entropy.
We analyze the conditions for purity of states and show that for a special
choice of the diffusion coefficients, the correlated coherent states (squeezed
coherent states) are the only states which remain pure all the time during the
evolution of the considered system. These states are also the most stable under
evolution in the presence of the environment and play an important role in the
description of environment induced decoherence.Comment: 41 pages, LaTe
Quantum decoherence of the damped harmonic oscillator
In the framework of the Lindblad theory for open quantum systems, we
determine the degree of quantum decoherence of a harmonic oscillator
interacting with a thermal bath. It is found that the system manifests a
quantum decoherence which is more and more significant in time. We also
calculate the decoherence time and show that it has the same scale as the time
after which thermal fluctuations become comparable with quantum fluctuations.Comment: Talk at the XI International Conference on Quantum Optics
(ICQO'2006), May 2006, Minsk (Belarus), 9 page
Quantum decoherence and classical correlations of the harmonic oscillator in the Lindblad theory
In the framework of the Lindblad theory for open quantum systems we determine
the degree of quantum decoherence and classical correlations of a harmonic
oscillator interacting with a thermal bath. The transition from quantum to
classical behaviour of the considered system is analyzed and it is shown that
the classicality takes place during a finite interval of time. We calculate
also the decoherence time and show that it has the same scale as the time after
which statistical fluctuations become comparable with quantum fluctuations.Comment: 24 pages, 8 figure
Dissipative tunneling through a parabolic potential in the Lindblad theory of open quantum systems
By using the Lindblad theory for open quantum systems, an analytical
expression of the tunneling probability through an inverted parabola is
obtained. This penetration probability depends on the environment coefficients.
It is shown that the tunneling probability increases with the dissipation and
the temperature of the thermal bath.Comment: 16 pages, 6 figure
Phase Space Representation for Open Quantum Systems within the Lindblad Theory
The Lindblad master equation for an open quantum system with a Hamiltonian
containing an arbitrary potential is written as an equation for the Wigner
distribution function in the phase space representation. The time derivative of
this function is given by a sum of three parts: the classical one, the quantum
corrections and the contribution due to the opening of the system. In the
particular case of a harmonic oscillator, quantum corrections do not exist.Comment: 19 pages, Latex, accepted for publication in Int. J. Mod. Phys.
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