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O. V. Man'ko

Publications and source records attributed to O. V. Man'ko.

27 records · Page 2Linked to original sources
arXiv2002

Reduced density matrices of oscillator systems

We study the evolution of an oscillator interacting via the most general bilinear coupling (with time-independent coefficients) with an ``environment'' consisting of a set of other harmonic oscillators. We are mainly interested in a possibility of using the Fokker-Planck equation to describe this evolution. Studying different interaction Hamiltonians, we show that unambiguous reduction to the Fokker-Planck equation is possible only within the framework of the so called rotating-wave approximation. As special cases we consider in detail the evolution of two coupled oscillators and relaxation of a charged oscillator in a uniform magnetic field.

quant-ph↗
arXiv2000

The Pauli Equation for Probability Distributions

The "marginal" distributions for measurable coordinate and spin projection is introduced. Then, the analog of the Pauli equation for spin-1/2 particle is obtained for such probability distributions instead of the usual wave functions. That allows a classical-like approach to quantum mechanics. Some illuminating examples are presented.

quant-ph↗
arXiv1998

Energy-Sensitive and "Classical-like" Distances Between Quantum States

We introduce the concept of the ``polarized'' distance, which distinguishes the orthogonal states with different energies. We also give new inequalities for the known Hilbert-Schmidt distance between neighbouring states and express this distance in terms of the quasiprobability distributions and the normally ordered moments. Besides, we discuss the distance problem in the framework of the recently proposed ``classical-like'' formulation of quantum mechanics, based on the symplectic tomography scheme. The examples of the Fock, coherent, ``Schroedinger cats,'' squeezed, phase, and thermal states are considered.

quant-ph↗
arXiv1995

Squeezed and Correlated States of Quantum Fields and Multiplicity Particle Distributions

The primary aim of the present paper is to attract the attention of particle physicists to new developments in studying squeezed and correlated states of the electromagnetic field as well as of those working on the latest topic to new findings about multiplicity distributions in quantum chromodynamics. The new types of nonclassical states used in quantum optics as squeezed states, correlated states, even and odd coherent states (Schrödinger cat states) for one--mode and multimode interaction are reviewed. Their distribution functions are analyzed according to the method used first for multiplicity distributions in high energy particle interactions. The phenomenon of oscillations of particle distribution functions of the squeezed fields is described and confronted to the phenomenon of oscillations of cumulant moments of some distributions for squeezed and correlated field states. Possible extension of the method to fields different from the electromagnetic field (gluons, pions, etc.) is speculated.

hep-ph↗
arXiv1995

Quantum Oscillator with Kronig-Penney Excitation in Different Regimes of Damping

There are discussed the exact solution of the time--dependent Schrödinger equation for a damped quantum oscillator subject to a periodical frequency delta--kicks describing squeezed states which are expressed in terms of Chebyshev polynomials. The cases of strong and weak damping are investigated in the frame of Caldirola--Kanai model.

quant-ph↗
arXiv1993

Thermal noise and oscillations of photon distribution for squeezed and correlated light

The oscillations of photon distribution function for squeezed and correlated light are shown to decrease when the temperature increases.The influence of the squeezing parameter and photon quadrature correlation coefficient on the photon distribution oscillations at nonzero temperatures is studied. The connection of deformation of Planck distribution formula with oscillations of distribution for squeezed and correlated light is discussed.

hep-th↗
arXiv1993

Multidimensional Hermite polynomials and photon distribution for polymode mixed light

For N-mode light described by the Wigner function of generic Gaussian form the photon distribution function is obtained explicitly and expressed in terms of Hermite polynomial of $2N$ variables with equal pairs of indices.The mean values and dispersions of photon numbers are obtained for this generic mixed state.Generating function for photon distribution is obtained explicitly. The expression for $N$-mode photon distribution function for squeezed photon number states in terms of Hermite polynomials of $2N$ variables and for squeezed coherent states in terms of Hermite polynomials of $N$ variables is discussed.

hep-th↗
arXiv1993

Photon distribution for one mode mixed light with generic gaussian Wigner function

For one-mode light described by the Wigner function of generic Gaussian form the photon distribution function is obtained explicitly and expressed in terms of Hermite polynomials of two variables.The mean values and dispersions of photon numbers are obtained for this generic %mixed state.Generating function for photon distribution is discussed.Known partial cases of thermal state,correlated state,squeezed state and coherent state are considered.The connection of Schrodinger uncertainty relation for quadratures with photon distribution is demonstrated explicitly.

hep-th↗