11 research outputs found
Wehrl information entropy and phase distributions of Schrodinger cat and cat-like states
The Wehrl information entropy and its phase density, the so-called Wehrl
phase distribution, are applied to describe Schr\"odinger cat and cat-like
(kitten) states. The advantages of the Wehrl phase distribution over the Wehrl
entropy in a description of the superposition principle are presented. The
entropic measures are compared with a conventional phase distribution from the
Husimi Q-function. Compact-form formulae for the entropic measures are found
for superpositions of well-separated states. Examples of Schr\"odinger cats
(including even, odd and Yurke-Stoler coherent states), as well as the cat-like
states generated in Kerr medium are analyzed in detail. It is shown that, in
contrast to the Wehrl entropy, the Wehrl phase distribution properly
distinguishes between different superpositions of unequally-weighted states in
respect to their number and phase-space configuration.Comment: 10 pages, 4 figure
Quantum statistical properties of the radiation field in a cavity with a movable mirror
A quantum system composed of a cavity radiation field interacting with a
movable mirror is considered and quantum statistical properties of the field
are studied. Such a system can serve in principle as an idealized meter for
detection of a weak classical force coupled to the mirror which is modelled by
a quantum harmonic oscillator. It is shown that the standard quantum limit on
the measurement of the mirror position arises naturally from the properties of
the system during its dynamical evolution. However, the force detection
sensitivity of the system falls short of the corresponding standard quantum
limit. We also study the effect of the nonlinear interaction between the moving
mirror and the radiation pressure on the quadrature fluctuations of the
initially coherent cavity field.Comment: REVTeX, 9 pages, 5 figures. More info on
http://www.ligo.caltech.edu/~cbrif/science.htm
Quantum dynamics and statistics of two coupled down-conversion processes
In the framework of Heisenberg-Langevin theory the dynamical and statistical
effects arising from the linear interaction of two nondegenerate
down-conversion processes are investigated. Using the strong-pumping
approximation the analytical solution of equations of motion is calculated. The
phenomena reminiscent of Zeno and anti-Zeno effects are examined. The
possibility of phase-controlled and mismatch-controlled switching is
illustrated.Comment: 17 pages, 7 figure
The 1/N-expansion, quantum-classical correspondence and nonclassical states generation in dissipative higher-order anharmonic oscillators
We develop a method for the determination of thecdynamics of dissipative
quantum systems in the limit of large number of quanta N, based on the
1/N-expansion of Heidmann et al. [ Opt. Commun. 54, 189 (1985) ] and the
quantum-classical correspondence. Using this method, we find analytically the
dynamics of nonclassical states generation in the higher-order anharmonic
dissipative oscillators for an arbitrary temperature of a reservoir. We show
that the quantum correction to the classical motion increases with time
quadratically up to some maximal value, which is dependent on the degree of
nonlinearity and a damping constant, and then it decreases. Similarities and
differences with the corresponding behavior of the quantum corrections to the
classical motion in the Hamiltonian chaotic systems are discussed. We also
compare our results obtained for some limiting cases with the results obtained
by using other semiclassical tools and discuss the conditions for validity of
our approach.Comment: 15 pages, RevTEX (EPSF-style), 3 figs. Replaced with final version
(stylistic corrections
Generation of squeezed light in a nonlinear asymmetric directional coupler
We show that a nonlinear asymmetric directional coupler composed of a linear
waveguide and a nonlinear waveguide operating by nondegenerate parametric
amplification is an effective source of single-mode squeezed light. This is has
been demonstrated, under certain conditions and for specific modes, for
incident coherent beams in terms of the quasiprobability functions,
photon-number distribution and phase distribution.Comment: 19 pages, 5 figure
Phase properties of the superposition of squeezed and displaced number states
We show that a nonlinear asymmetric directional coupler composed of a linear
waveguide and a nonlinear waveguide operating by nondegenerate parametric
amplification is an effective source of single-mode squeezed light. This is has
been demonstrated, under certain conditions and for specific modes, for
incident coherent beams in terms of the quasiprobability functions,
photon-number distribution and phase distribution.Comment: 17 pages, 4 figure