Light Squeezing in the Jaynes-Cummings Model with Intensity-dependent Coupling

Abstract

We have found that in the intensity-dependent-coupling Jaynes-Cummings model with the coherent radiation field light squeezing exhibits periodical revivals. The influence of the initial states of the atom on the squeezing of light is investigated in detail.     

Collapse-revival Phenomenon in the Jaynes-Cummings Model Interacting with the Multiphoton Holstein-Primakoff SU(2) Coherent State

Abstract

We have analysed the behaviour of the atomic population inversion of the two-level atom interacting with a single-mode field initially prepared in the multiphoton Holstein-Primakoff SU(2) coherent state. It is shown that the behaviour of the atomic inversion depends on the parameters characterizing the initial state of the field. In particular, the atomic inversion can exhibit periodical oscillations as well as the collapse-revival phenomenon.     

N-level Atom Interacting with Single-mode Radiation Field: An Exactly Solvable Model with Multiphoton Transitions and Intensity-dependent Coupling

Abstract

We study the dynamics of an N-level atom coupled in a lossless cavity to a single-mode near-resonant quantized field. The atomic levels are coupled by the multiphoton transitions and the coupling constants between the field and the atomic levels are supposed to be intensity dependent. We find the exact solution for the state vector describing the dynamics of the atom-plus-field system. As an illustration we use the model for studying (i) the time evolution of the atomic occupation probability with the initially coherent field and (ii) the light squeezing, when the cavity field is initially in the vacuum state and the atom is prepared in the atomic ‘coherent state’ (a superposition of atomic states).     

Squeezing of Spectral Components in the Jaynes-Cummings Model

Abstract

Squeezing of spectral components of a fluorescence field in the framework of the Jaynes-Cummings model has been studied. It has been shown that squeezing is observed only in sidebands of the fluorescence field. The degree of squeezing increases as the intensity of the cavity mode is increased. Contrary to squeezing in the cavity mode (see Kuklinski and Madajczyk [14] a large degree of squeezing in sidebands of the fluorescence field is observed in the short-time limit.     

Effects of Even and Odd Coherent States on the Evolution of the Two-photon Jaynes-Cummings model

We discuss the two-photon Jaynes-Cummings model prepared in even or odd coherent states in terms of its dynamical evolution and the statistical aspects of field, such as intensity-intensity correlation and squeezing. Time evolution of the quasiprobability function has also been investigated. This study reveals how the quantum interference present in the even and odd coherent states affects the nonlinear process of the two-photon transition.     

SU(1,1) Squeezing of SU(1,1) Generalized Coherent States

Abstract

In this paper we have introduced a new class of the SU(1,1) coherent states which are the eigenstates of the generalized annihilation operator K_. We have also studied the SU(1,1) squeezing of the SU(1,1) generalized coherent states interacting with a nonlinear medium modelled as an anharmonic oscillator.     

Effective Dipole Squeezing in the Non-degenerate Two-photon Jaynes-Cummings Model with Superposition State Preparation

Abstract

Effective dipole squeezing in the non-degenerate two-photon Jaynes-Cummings model for atom and fields initially prepared in superposition of states is investigated. It is shown that the squeezing can be exhibited in certain periods of time but it cannot be achieved for atomic spontaneous radiation processes.     

Coherent States of a Harmonic Oscillator in a Finite-dimensional Hilbert Space and Their Squeezing Properties

Abstract

New coherent states of a harmonic oscillator in a finite-dimensional Fock space are introduced. Some properties of these coherent states are discussed. The second-order squeezing of these coherent states with respect to the quadrature operators is studied in detail. In particular, for a two-state system the arbitrary higher-order squeezing of these states is investigated. It is shown that these coherent states exhibit much richer squeezing properties than the coherent states of a usual harmonic oscillator in an infinite-dimensional Fock space. It is found that these coherent states have not only second-order squeezing but also higher-order squeezing with respect to the quadrature operators of the field under consideration.     

The Jaynes-Cummings Model with a q Analogue of a Coherent State

Abstract

In this paper we study the time evolution of the atomic inversion of the two-level atom which is coupled to the q analogue of a single mode of the bosonic field. The q field under consideration is supposed to be prepared initially in the q analogue of Glauber's coherent state. We find that q deformation of Heisenberg algebra may correspond to some effective nonlinear interaction of the cavity mode.     

Long Time Behaviour of the Field in a Lossless Micromaser with Intensity-dependent Coupling Constant

Abstract

Using the asymptotic form of the density matrix the role of the non-diagonal elements of the density matrix is estimated in the lossless micromaser model based on the Jaynes-Cummings model with intensity dependent coupling constant. It is shown that a certain type of a (almost pure) multiphoton state can be generated in this system.     

Squeezing Properties and Photon Statistics in Multiphoton Processes with Radiative Damping of the Atomic Levels

Abstract

A model for the master equation of multiphoton processes with radiative damping of the atomic levels is proposed and a matrix method employed to solve exactly the rate equations for the matrix elements of the reduced density operator in the Fock representation. This model has been applied to the study of the low-noise properties of squeezed light in an all-optical transmission link formed from alternating sections of linear and nonlinear attenuating fibre and optical amplifiers. When the attenuators present radiative damping of the atomic levels (the lower atomic state is not the ground state) the signal-to-noise ratio is enhanced with respect to the case in which the lower atomic level is the ground state. The enhancement is improved when the input light is squeezed. The statistical properties of linear and two-photon amplification with an absorption process which exhibits radiative damping have also been analysed for coherent and squeezed inputs. The second-order fluctuations are reduced when radiative damping in the absorption process is considered except in the case of two-photon absorption for small values of the saturation parameter s_a . When the value of this parameter is increased the behaviour of the fluctuations changes and the noise is reduced. These results could be of interest in all-optical transmission links and are improved when the input light is squeezed.     

On the Interaction of Two-level Atoms with Superpositions of Coherent States of Light

Abstract

In this paper we study the decoherence process occurring when a field prepared in quantum superpositions of coherent states (Schrödinger cats) interacts with a two-level atom in the framework of the Jaynes-Cummings model. We emphasize the influence of the relative phase in the initial superposition state on the purity of the field during the evolution     

Squeezing in Finite Superpositions of Photon-number States without the Vacuum

Abstract

We show that a finite superposition of photon-number states without the vacuum state can lead to squeezed fluctuations. The properties of these states are discussed.     

Sub-Poissonian Photon Statistics and Higher-order Squeezing in the Light Amplifier with Input Binomial States

Abstract

We make a comparison between the necessary and sufficient conditions on the gain of the linear amplifier under which the light output exhibits sub-Poissonian photon statistics or squeezing and exact numerical results, obtained by solving the master equation by means of matrix procedures, and find good agreement. We find numerically that higher-order squeezing persists in a region in which sub-Poissonian statistics and second-order squeezing have already disappeared, for certain parameter ranges of input binomial states.     

Interaction of Superpositions of Coherent States of Light with Two-level Atoms

Abstract

We investigate some of the basic features of the interaction of superpositions of coherent states of light with two-level atoms in the framework of the Jaynes-Cummings model. We compare the behaviour of the system in the case of having a coherent superposition state and a statistical mixture of coherent states as an initial field. We investigate the collapses and revivals of the atomic inversion by studying the evolution of the Q function of the cavity field. We also establish the connection between the purity of the field and the collapses and revivals of the atomic inversion.     

Evolution of Coherent States in a Dispersionless Fibre with Saturable Nonlinearity and the Generation of Macroscopic Quantum-superposition States

Abstract

We study the evolution of a initially coherent state of an electromagnetic field propagating in a Kerr medium with saturable nonlinearity. By using the quantum phase distribution formalism, we analyse the dependence of the output signal phase configuration upon input field amplitude. We observe that the saturation of the nonlinear contribution of the refractive index of the propagation medium introduces interference effects that compromise the observation of macroscopically well distinguishable components of the output state. For input amplitudes much larger than a characteristic saturation amplitude the final state differs from the input state only by an overall phase shift. Possible relevance of the present results in the experimental search of Schrödinger cat-like states using semiconductor-doped glass optical fibres is discussed.     

On the Fourth Order Hamiltonian of an Asymmetric Rotor Molecule of Orthorhombic Symmetry

The fourth order Hamiltonian of an asymmetric rotor molecule of orthorhombic symmetry given recently has been considerably reduced in complexity through the use of equations derived from the basic relationship among the angular momentum operators. The reduced Hamiltonian obtained provides a most convenient starting point for the calculation of rotational energy levels from a solution of the complete secular equation, for a perturbation theory solution to the problem of centrifugal distortion, and for the deduction of sum rules among the energy levels.     

On the Electrical Interaction as an Elastic Coupling Through the Flux Lines

By using the elastic coupling through the field lines, we present a new theoretical treatment of the electrical interaction. We consider both static and oscillatory fields. The obtained results show that the static interaction energy is in reverse proportion with respect to the distance between the centers of the two bodies whereas the oscillatory interaction energy contains two terms: one which is in reverse proportion with respect to the third power of this distance and the other which is in reverse proportion with this distance. The latter term appears because of retardation. An attraction between the two charged particles of the same sign may appear if the oscillatory energy of interaction is larger than the static energy of interaction. This is the case of the electron pairs in superconductors.     

Vortex States of Two-Component Bose-Einstein Condensates with and Without Internal Josephson Coupling

We study the equilibrium structure of vortex states in rotating two-component Bose–Einstein condensates. Each component forms respectively a vortex state and the intercomponent coupling makes a rich variety of structures combining these two vortex states. We show a phase diagram of stable vortex states in the intercomponent-coupling versus rotation-frequency. As the intercomponent coupling and the rotation frequency increase, the interlocked vortex lattices undergo structural transition from a triangular lattice to a square one. In a strongly phase-separated regime, vortex cores in each component overlap, forming double-core vortex lattices and serpentine vortex sheets. We also discuss the effect of Josephson coupling between two components on the vortex states.