Two-mode Radiation Field Research Articles

Reduced bases for a three-level atom interacting with a two-mode radiation field

Reduced bases are obtained for a single three-level atom interacting dipolarly with a two-mode electromagnetic field in a cavity. A truncation scheme for the infinite dimensional Hilbert space of the system is proposed, which we take it as the exact ground-state solution. This is used to determine the quantum phase diagram of the atomic $\mathrm{\ensuremath{\Lambda}}$ configuration and to judge the goodness of the reduced bases. This provides us with a mathematical technique that can be used to solve systems where the number of atoms and excitations grow, yielding a Hilbert space with enormous dimensions, more effectively than with the currently available methods. Additionally, the sudden changes suffered by the ground-state solution can be observed through the calculation of the purity and the occupation probabilities.

Superposition and entanglement of two-mode squeezed vacuum states

In this paper, by using the parity operator as well as the two-mode squeezing operator, we define new operators which by the action of them on the vacuum state of the two-mode radiation field, superposition of two two-mode squeezed vacuum states and entangled two-mode squeezed vacuum states are generated.

On a moving four-level N-type atom interacting with two-mode cavity field in the presence of the cross-Kerr medium

In this paper, some properties through the moving four-level [Formula: see text]-type atom interacting with a two-mode radiation field are presented. We study this system in the presence of the nonlinearity. The exact solution of this model is given by using the Schrödinger equation when the atom and the field are initially in an excited state and a squeezed state, respectively. We employed the results to perform a careful investigation of the temporal evolution of the cross-correlation function, the momentum increment, the difference mean photon numbers and the normal squeezing. The influence of the Kerr and the cross-Kerr medium parameters on these aspects is examined. It is found that the atom-field properties are affected by the changing of these parameters.

Number-phase entropic squeezing and nonclassical properties of a three-level atom interacting with a two-mode field: intensity-dependent coupling, deformed Kerr medium, and detuning effects

In this paper, we follow the model presented in our previous work [J. Opt. Soc. Am. B30, 1109 (2013)], in which the interaction between a Λ-type three-level atom and a quantized two-mode radiation field in a cavity in the presence of nonlinearities was studied. After giving a brief review of the procedure for obtaining the state vector of the atom-field system, we investigated some further interesting and important physical features of the whole system state, which are of particular interest to the quantum optics field of research, i.e., the number-phase entropic uncertainty relation (based on the two-mode Pegg–Barnett formalism) and a few of the nonclassicality signs that consist of sub-Poissonian statistics, Cauchy–Schwartz inequality, and two types of squeezing phenomena. During our presentation, the effects of intensity-dependent coupling, deformed Kerr medium, and the detuning parameters on the depth and domain of each of the mentioned nonclassical criteria of the considered quantum system are described in detail. The results show that each of the mentioned nonclassicality aspects can be obtained by appropriately choosing the related parameters.

Entanglement of a two two-level atom interacting with electromagnetic field in the presence of converter terms

The exact solution of the problem of two two-level atoms interacting with a two-mode radiation field in the presence of a parametric converter term is presented. More precisely we have considered a Hamiltonian model that includes two types of interaction: one is the field–field (frequency converter type) and the other is the atom–field interaction. By introducing a canonical transformation an exact solution of the wave function in the Schrödinger picture is obtained. The result presented in this context is used to discuss the atomic inversion as well as the entropy squeezing and variance squeezing phenomena. We use the von Neuman entropy to measure the degree of entanglement between the atom and the field. These aspects are sensitive to changes in the converter parameter.

Study of Concurrence and D-Concurrence on Two-Qubits Resulted in Pair Coherent States in Language of SU(2) Coherent States

Pair coherent state, is a state of a two-mode radiation field that is known as a state with non-gaussian wave function. In this paper, study on the pair coherent state, we notice that with superposition of two first terms of this states, one two-qubits formed. Because of the importance of two-qubits in theory of quantum entanglement, with two different measures with the title of concurrence and D-concurrence, we have studied the amount of entanglement and discussed its details. At the end, we describe these measures for pair coherent states as a function of the amplitude of the SU(2) coherent states.

D-Concurrence Bounds for Pair Coherent States

Pair coherent state can be regarded as a state of a two-mode radiation field such that the wave function is non-Gaussian and infinite dimensional, too. Since the entanglement for high dimensional mixed states is difficult to calculate, it is necessary to find bound for entanglement measures. In this paper, some features of quantum entanglement for the pair coherent state are studied and also the upper and lower bounds for D-concurrence (a new entanglement measure) over this state are obtained.

Atom-field entanglement in two-atom Jaynes–Cummings model with nondegenerate two-photon transitions

An exact solution of the problem of two two-level atoms with nondegenerate two-photon transitions and nondegenerate Raman transitions interacting with two-mode radiation field is presented. Asymptotic solutions for system state vectors are obtained in the approximation of large initial coherent fields. The atom-field entanglement is investigated on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process for both models is shown. Conditions and times of disentanglement are derived.

Solutions of two-mode Jaynes-Cummings models

A simple procedure to solve two fully quantized non-linear Jaynes-Cummings models is presented, one in which an atom interacts with a two-mode radiation field in a Raman-type process and the other involving multiphoton interaction between the two-mode field and the atom. Effect of intensity-dependent coupling between the field and the atom in both the above-mentioned cases has also been investigated. The unitary transformation method presented here not only solves the time-dependent problem but also permits a determination of the eigensolutions of the interacting Hamiltonian at the same time. Graphical features of the time dependence of the population inversion have been analysed when one of the field modes is prepared initially in a coherent state while the other one in a vacuum state.

Quantitative measures of entanglement in pair-coherent states

The pair coherent states for a two-mode radiation field are known to belong to a family of states with non-Gaussian wave function. The nature of quantum entanglement between the two modes and some features of non-classicality are studied for such states. The existing criteria for inseparability are examined in the context of pair coherent states.

Characteristics of Aharonov–Bohm Electron Interference in Two-Mode Squeezed Vacuum

Electron interference related to Aharonov–Bohm effect in the presence of the two-mode quantized radiation field is investigated. Characteristics of Shapiro steps, the visibility of the interference fringe and the temporal behavior of electron interference in correlated and uncorrelated two-mode radiation field are discussed. It is shown that for the correlated two-mode squeezed vacuum the integer Shapiro steps are obtained and the time evolution of the intensity of electron interference can exhibit very interesting periodic spontaneous collapse and revival (CR), while for the uncorrelated two-mode coherent state the fractional Shapiro steps are obtained and the CR phenomenon does not occur. In addition, the relation between CR and the quantum fluctuation in electron interference is also discussed.

Vortex states for the quantized radiation field

We study the properties of wave-packet states with vortex structure. In particular we present the characteristics of a two-mode radiation field characterized by a configuration-space wave function Ψ v =(x-iy) m e- (x 2 +y 2 ) /2σ 2 . We show the generation of such states by the interaction of Λ systems with squeezed radiation in a two-mode cavity. The two modes are correlated due to entanglement, which also produces the mixed state of each mode even though the state of the two-mode field is a pure state.

Derivation of cooperative-dynamic equations for an ensemble of three-level atoms in a coherent electromagnetic field

Equations for the density matrix of three-level atoms interacting collectively with a two-mode radiation field are derived for level schemes of three types within the framework of a formalism with secondary quantization of the electromagnetic field.

State preparation via quantum coherence and continuous measurement.

The theory of continuous measurement is generalized so as to be applicable to a two-mode radiation field whose properties are monitored by using a \ensuremath{\Lambda} system with initial coherence between two ground states. The two-mode system is shown to offer the possibility of generating a number of new quantum states. Quantum statistics of the field following continuous measurements is calculated. Results for the phase distribution, quasiprobability distribution, and the photon-number distribution of the resulting field are also presented.

Eigenstates of the phase operator à la Dirac for a two-mode field

The eigenstates of the phase operator are calculated for a two-mode radiation field subject to the condition that these be also the eigenstates of the operator corresponding to the difference q of the number of photons in the two modes. The phase distribution associated with such states has the form 1 [1 + F sin 2 ( θ 2 )] . In the special case q = 0, these eigenstates become identical to the two-mode squeezed vacuum.

SQUEEZING PROPERTIES OF COUPLED NONLINEAR OSCILLATORS

In this paper the squeezing properties of the two-mode radiation field interacting with a nonliner nonabsorbing Kerr-like medium modelled as a two-mode anharmonic oscillator are studied. Time evolution of the variances of the radiation field initially prepared in the two-mode coherent state as well as the two-mode squeezed vacuum state are analyzed. In particular, it is shown that in the case when the radiation field is initially prepared in the two-mode coherent state the interaction between two modes leads to a high degree of squeezing.

On a Jaynes-Cummings type model with multiphoton transitions

The authors present a quantum electrodynamic model, soluble in the dipole and rotating wave approximation, for a three-level atom interacting with a two-mode resonant radiation field through the multiphoton transition mechanism. Population dynamics and photon statistics in this Jaynes-Cummings type model are examined.

Coherent properties of the stimulated emission from a three-level atom.

First-order correlation functions of the electric field and photon-number probabilities in the case of a three-level atom interacting with two-mode radiation field are obtained to investigate the coherent properties of the stimulated emission under different initial conditions. It is found that double stimulation will cause the field to approach its initial coherent state and the oscillation of the photon-number probabilities to collapse and revive.