14 research outputs found
Nonclassicality and the concept of local constraints on the photon number distribution
We exploit results from the classical Stieltjes moment problem to bring out
the totality of all the information regarding phase insensitive nonclassicality
of a state as captured by the photon number distribution p_n. Central to our
approach is the realization that n !p_n constitutes the sequence of moments of
a (quasi) probability distribution, notwithstanding the fact that p_n can by
itself be regarded as a probability distribution. This leads to classicality
restrictions on p_n that are local in n involving p_n's for only a small number
of consecutive n's, enabling a critical examination of the conjecture that
oscillation in p_n is a signature of nonclassicality.Comment: Five pages in revtex with one ps figure included using eps
Necessary and Sufficient Classicality Conditions on Photon Number Distributions
We exploit results on the classical Stieltjes moment problem to obtain
completely explicit necessary and sufficient conditions for the photon number
distribution p(n) of a radiation field mode to be classical. These conditions
are given in two forms - respectively local and global in the individual photon
number probabilities. Central to the first approach is the recognition of the
important fact that the quantities n!p(n) are moments of a quasiprobability
distribution, notwithstanding the fact that p(n)'s can by themselves be
considered as a probability distribution over the nonnegative integers. This
leads to local classicality conditions involving p(n)'s for only a small number
of values of n. This local approach enables us to present detailed quantitative
statements on the connection between nonclassicality and oscillations in the
photon number distribution. The second approach is in terms of the traditional
factorial moments of p(n). Equivalence of the two approaches is established.Comment: 12-pages in revtex with three ps figure included using eps
Revival-collapse phenomenon in the quadrature squeezing of the multiphoton Jaynes-Cummings model with the binomial states
In this paper we study the interaction between two-level atom and quantized
single-mode field, namely, Jaynes-Cummings model (JCM). The field and the atom
are initially prepared in the binomial state and the excited atomic state,
respectively. For this system we prove that the revival-collapse phenomenon
exhibited in the atomic inversion of the standard JCM can be numerically
(naturally) manifested in the evolution of the squeezing factor of the
three-photon (standard) JCM provided that the initial photon-number
distribution of the radiation has a smooth envelope.Comment: 14 pages, 4 figures, Comments are most welcom
Quantum properties of the parametric amplifier with and without pumping field fluctuations
The parametric amplifier with and without the pumping fluctuations of
coupling function is considered when the fields are initially prepared in
coherent light.
The pumping fluctuations are assumed to be normally distributed with
time-dependent variance. The effects of antibunching and anticorrelation of
photons on the photon distribution, correlation between modes and factorial
moments are demonstrated. A possible enhancement of photon antibunching for
certain values of initial mean photon numbers is shown and discussed. We have
shown also that new states (called modified squeezed vacuum states or even
thermal states) can be generated from such an interaction. Further, we have
demonstrated that the sum photon-number distribution can exhibit collapses and
revivals in the photon-number domain somewhat similar to those known in the
Jaynes-Cummings model.Comment: 17 pages, 6figure
Gaussian Wigner distributions and hierarchies of nonclassical states in quantum optics-The single mode case
A recently introduced hierarchy of states of a single mode quantised
radiation field is examined for the case of centered Guassian Wigner
distributions. It is found that the onset of squeezing among such states
signals the transition to the strongly nonclassical regime. Interesting
consequences for the photon number distribution, and explicit representations
for them, are presented.Comment: 11 Pages Revtex one eps figure. Replaced with minor changes in ref
Anti-N-Methyl-D-Aspartate (NMDA) Receptor Encephalitis Mimicking a Primary Psychiatric Disorder in an Adolescent.
Anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis likely has a wider clinical spectrum than previously recognized. This article reports a previously healthy 16-year-old girl who was diagnosed with anti-NMDA receptor encephalitis 3 months after onset of severe depression with psychotic features. She had no neurological manifestations, and cerebral magnetic resonance imaging (MRI) was normal. Slow background on electroencephalogram and an oligoclonal band in the cerebrospinal fluid prompted the search for anti-NMDA receptor antibodies. She markedly improved over time but remained with mild neuropsychological sequelae after a trial of late immunotherapy. Only a high index of suspicion enables recognition of the milder forms of the disease masquerading as primary psychiatric disorders