8 research outputs found
When is Quantum Decoherence Dynamics Classical?
A direct classical analog of quantum decoherence is introduced. Similarities
and differences between decoherence dynamics examined quantum mechanically and
classically are exposed via a second-order perturbative treatment and via a
strong decoherence theory, showing a strong dependence on the nature of the
system-environment coupling. For example, for the traditionally assumed linear
coupling, the classical and quantum results are shown to be in exact agreement.Comment: 5 pages, no figures, to appear in Physical Review Letter
Decoherence in a single trapped ion due to engineered reservoir
The decoherence in trapped ion induced by coupling the ion to the engineered
reservoir is studied in this paper. The engineered reservoir is simulated by
random variations in the trap frequency, and the trapped ion is treated as a
two-level system driven by a far off-resonant plane wave laser field. The
dependence of the decoherence rate on the amplitude of the superposition state
is given.Comment: 4 pages, 2 figure
Wigner functions, squeezing properties and slow decoherence of atomic Schrodinger cats
We consider a class of states in an ensemble of two-level atoms: a
superposition of two distinct atomic coherent states, which can be regarded as
atomic analogues of the states usually called Schrodinger cat states in quantum
optics. According to the relation of the constituents we define polar and
nonpolar cat states. The properties of these are investigated by the aid of the
spherical Wigner function. We show that nonpolar cat states generally exhibit
squeezing, the measure of which depends on the separation of the components of
the cat, and also on the number of the constituent atoms. By solving the master
equation for the polar cat state embedded in an external environment, we
determine the characteristic times of decoherence, dissipation and also the
characteristic time of a new parameter, the non-classicality of the state. This
latter one is introduced by the help of the Wigner function, which is used also
to visualize the process. The dependence of the characteristic times on the
number of atoms of the cat and on the temperature of the environment shows that
the decoherence of polar cat states is surprisingly slow.Comment: RevTeX, 14 pages including 8 PostScript figures. High quality
versions of Figures 1, 3, 5, 7 and 8 are available at
http://www.jate.u-szeged.hu/~benedict/asc_figures.html . (Submitted to
Physical Review A: March 26, 1999.