Two-mode Optical Fields Research Articles

Unambiguous Discrimination between Coherent States of the Two-Mode Optical Field

The procedure of quantum measurement—unambiguous discrimination—of four two-mode coherent states of the optical field which are of interest for information transmission by the optical communication channel is studied. It is shown that complex conjugation of the amplitude of one of the modes leads to better discriminability between the states. An interferometric scheme for unambiguous discrimination between such states is proposed and the probability of successful discrimination is found. Applications of the considered set of states in quantum cryptography, quantum teleportation, and optical communication with a high level of losses are discussed.

Time Evolution and Temperature Variation of the Squeezing-Chaotic Mixed Two-Mode Optical Field in One-Mode Diffusion Channel

In this paper we theoretically investigate how the squeezing-chaotic mixed two-mode optical field described by the density operator

Temperature Effect of Measuring One of the Two Modes of a New Two-Mode Optical Field

We propose a new two-mode optical field which involves both squeezing and chaotic behaviour. We find that measuring one of the two modes of this new two-mode optical field (theoretically it is performed by partial tracing over one of the two modes of this optical field’s density operator) leads to different chaotic field with different temperature. This means that a different-mode measurement for the new optical field will cause a temperature effect which has been unnoticed before. Such kind of new photon field can be generated when a two-mode squeezed state is passing through a single-mode damping channel.

Nonclassical properties of nonlocal coherent photon-added two-mode squeezed thermal states

We investigate theoretically the nonclassical properties of the nonlocal coherent two-mode photon-added squeezed thermal state such as cross correlation function, antibunching effect, and inseparability. The results show the excitation number has significant effect on these properties. The cross anticorrelation effect will strengthen with decreasing of the excitation number but the cross correlation effect will weaken with decreasing of the excitation number. The antibunching effect of two-mode optical fields can be observed only if the excitation number S<2. The entanglement between two modes of optical fields can be observed only if s≤2.

Quantum Fisher information flow and entanglement in pair coherent states

Realistic quantum systems are the main part of quantum information technology, which causes the rapid destruction of crucial quantum properties. Therefore, the unavoidable interaction between quantum systems, understanding the dynamics of entanglement indicators and finding the correlation between different phenomena may stimulate great interest. In this article the quantum Fisher information and nonlocal correlation between a single qubit and two-mode optical field initially in pair coherent states have investigated. We examine the impact of the qubit motion and intensity dependent function on the flow of quantum Fisher information and quantum entanglement during the time evolution. We discuss the relationship between quantum Fisher information flow and quantum entanglement in the case of moving and unmoving single qubit.

Coherent control of atom dipole squeezing and violation of Cauchy-Schwarz inequality

By studying the interaction of isolated two-level atom with two-mode entangled coherent state optical field, the time evolution of dipole squeezing quantum effect in the system is investigated in detail. The results show that the properties of interaction coherent mode determine the degree of atom dipole squeezing. Parameter ΔV of violation of Cauchy-Schwarz inequality of the interaction system is defined. Time evolution of parameter ΔVis studied, and it can be seen evidently from the results that the degree of violation of Cauchy-Schwarz inequality accords with the nonclassical property of interaction system. Through tuning the parameter of the coherent field, we can easily perform the remote control of the noncommercial properties.

Deriving operator identities by two-mode coherent-entangled state representation

On the basis of the new introduced two-mode coherent entangled state representation and the technique of integration within an ordered product of operators, we derived some operator identities of the operator functions about the quadrature of two-mode optical field, such as （X1+X2）/21/2 and （μX1+νX2）/λ, which should be helpful to further studying the high order squeezing properties of optical field and to constructing some generalized-squeezed states.

An Intuitive Expression for Inseparability Condition of aTwo-Mode Squeezed Vacuum State in a Thermal Environment

Considering the propagation of a two-mode optical field that isinitially in a squeezed vacuum state in a thermal environment, we obtainan intuitive expression for inseparability condition of the two-modemixed state which is given in the coherent state representation. Thiscondition shows that the two modes have quantum entanglement if and onlyif the coefficient of the correlation term between the two modes islarger than that of the off-diagonal term of each mode in the densitymatrix. We find that even if the quantum channel is dynamically coupledto the thermal environment, the fidelity for teleporting coherent stateslarger than 1/2 is still the criterion for quantum teleportation. Wealso show that the entanglement, squeezing and quantum teleportationconditions are always consistent with each other.

Phase measurement and generation of arbitrary superposition of Fock states

We present two schemes for measuring quantum phase probability distribution of single-mode optical fields, and show that the proposed setups can be applied to generate arbitrary single-mode superposition of Fock states ∑ n=0 N C n | n〉 from a squeezed vacuum state. Compared with previous schemes, the present schemes only require squeezed vacuum states and coherent states as auxiliary resources and are more appropriate for experimental realization. Further we demonstrate the capability of the scheme in respect of a generalization to realize joint measurement of photon number sum and phase difference operators on two-mode optical fields, and generate arbitrary two-mode N-photon entangled states of the form ∑ n=0 N C n | n〉| N− n〉 from a pair of squeezed vacuum states.

Pancharatnam Phase of Two-Mode Optical Fields with Kerr Nonlinearity

The Pancharatnam phase when an ideal cavity is filled with a Kerr-like medium and coupling is affected through a nondegenerate Raman two-photon process is studied. A careful investigation is made seeking exact results on the temporal evolution of atomic inversion and Pancharatnam phase. We invoke the mathematical notion of maximum variation of a function to construct a measure for Pancharatnam phase fluctuations. It is shown that Pancharatnam phase contains explicit information about the statistics of the field and atomic coherence, and is also shown that addition of the Kerr medium has an important effect on the properties of this phase. The results show that the effect of the Kerr medium changes the quasiperiod of the Pancharatnam phase evolution. The influence of Stark shift on the atomic inversion and the Pancharatnam phase in both presence and absence of the nonlinear medium is examined. General conclusions reached are illustrated by numerical results.

Phase properties of two-mode gaussian light fields with application to Raman scattering

We investigate quantum phase properties of two-mode optical fields whose quasidistributions have Gaussian form. We show how to simplify the calculation of the joint phase distribution defined via radial integration of the quasidistribution related to s-ordering of the field operators. We find an analytical formula for the joint phase distribution when coherent components of both modes vanish. The general results are applied to analysis of quantum phase properties of the two-mode Stokes-anti-Stokes field generated by means of Raman scattering with a broad reservoir phonon system and strong coherent laser pumping.

A POSSIBLE CLASS OF TWO-MODE PHOTON STATES AND THEIR PROPERTIES

In this paper, a new class of two-mode optical field states is given. The quasi-spin coherent state is their lowest state. Their non-classical properties are discussed in detail.

Phase Properties of Two-Mode Optical Fields with Stark Shift and Kerr Nonlinearity

The influence of Stark shift on the phase properties when an ideal cavity is filled with a Kerr-like medium and coupling is effected through nondegenerate Raman two-photon processes is studied. This has been carried out using the Hermitian phase formalism of Pegg and Barnett. We find that the phase properties of the field reflect the collapses and revivals of the level occupation probabilities in most situations. The interaction brings about the symmetrical splitting of the phase probability distribution. A number of interesting features are found and discussed.

Production of two-mode optical Schrödinger catlike states via Kerr nonlinearity

The state evolution of a system of two-mode optical fields interacting with a Kerr medium is investigated. It is discovered that at some special times the system evolves into a quantum superposition of a finite number of different macroscopically distinguishable two-mode coherent states, i.e., so-called two-mode Schrödinger-cat states. Especially the two-mode Yurke-Stoler state is achieved at half of the period of the system by taking proper parameters. The influence of detuning and dissipation on two-mode Schrödinger-cat states is also discussed.

Non-classical photon statistics for two-mode optical fields

Non-classical photon statistics for two-mode optical fields

Non-classical photon statistics for two-mode optical fields

The non-classical property of subpoissonian photon statistics is extended from one to two-mode electromagnetic fields, incorporating the physically motivated property of invariance under passive unitary transformations. Applications to squeezed coherent states, squeezed thermal states, and superposition of coherent states are given. Dependences of extent of non-classical behaviour on the independent squeezing parameters are graphically displayed.