Entanglement for a Bimodal Cavity Field Interacting with a Two-Level Atom

Negativity has been adopted to investigate the entanglement in a system composed of a two-level atom and a two-mode cavity field. Effects of Kerr-like medium and the number of photon inside the cavity on the entanglement are studied. Our results show that atomic initial state must be superposed, so that the two cavity field modes can be entangled. Moreover, we also conclude that the number of photon in the two cavity mode should be equal. The interaction between modes, namely, the Kerr effect, has a significant negative contribution. Note that the atom frequency and the cavity frequency have an indistinguishable effect, so a corresponding approximation has been made in this article. These results may be useful for quantum information in optics systems.     

Entanglement for a Bimodal Cavity Field Interacting with a Two-Level Atom

Negativity has been adopted to investigate the entanglement in a system composed of a two-level atom and a two-mode cavity field. Effects of Kerr-like medium and the number of photon inside the cavity on the entanglement are studied. Our results show that atomic initial state must be superposed, so that the two cavityfield modes can be entangled. Moreover, we also conclude that the number of photon in the two cavity mode should be equal. The interaction between modes, namely, the Kerr effect, has a significant negative contribution. Note that the atom frequency and the cavity frequency have an indistinguishable effect, so a corresponding approximation has been made in this article. These results may be useful for quantum information in optics systems.     

Thermal Entanglement Between a Jaynes-Cummings Atom and an Isolated Atom

We studied the entanglement of a quantum system consisting of a Jaynes-Cummings atom, thermal lossless cavity and an isolated atom. The analytical expressions of the atom-atom negativity for separable and entangled initial atomic states were obtained. The influence of a detuning between the atomic transition frequency and the field frequency and direct dipole-dipole interaction on an atom-atom entanglement is examined. We showed that for a separable initial atomic states a detuning might cause high atom-atom entanglement in the presence of the dipole-dipole interaction. We also obtained that for an entangled initial atomic state a detuning causes a stabilization of an entanglement oscillations both for model with dipole-dipole interaction and model without such interaction.     

Dynamics of Entanglement between Moving Four-Level Atom and Single Mode Cavity Field

In this paper we are interested in studying the entanglement between a single four-level ladder-type atom interacting with one-mode cavity field when the atomic motion is taken into account. The exact solution of the model is obtained by using Schrodinger equation for a specific initial conditions. The field entropy of this system is investigated in the non-resonant case. The effects of the detuning parameter and the atomic motion on the entanglement degree are examined. These investigations show that both of the detuning and the atomic motion play important roles in the evolution of the von Neumann entropy and atomic populations. Finally, conclusions and some features are given.     

Entanglement Dynamics of a Three-Level Atom in Ξ Configuration

Dynamical behaviour of entanglement between the cavity mode and a three-level atom in the configuration is studied by making use of log-negativity. The influence of initial temperature of the thermal field and detuning on the entanglement is investigated. It is found that the maximal values of entanglement decreases with the temperature of the thermal field and can be controlled by the defaming.     

Spatial Electron Transitions in a Hydrogen-Like Atom with Photon Emission

Russian Physics Journal - For the first time, electron transitions in a hydrogen-like atom with changes in the spatial dimension D = 3 → D′ = 1, 2 and energy of its state accompanied by...     

Coherent Controlling Single Photon Asymmetric Transmission in the Atom Chirally Coupled Waveguide System

We theoretically investigate the influences of two coherent driving fields on the asymmetric transmission of single photon in the atom-waveguide system.The atom is considered as a A system.One transition of the atom chirally couples to the waveguide.The other transition is driven by two coherent driving fields.The transmission probabilities for the single photon incidents from the left(T_(lr)) and right(T_(lr)) are given respectively.The calculated results show that one can realize T_(lr)=0(T_(lr)≠0) or T_(lr)=0(T_(lr)≠0) by manipulating the phase difference between the two coherent driving Relds.The influence of the decay rate of the metastable state on the asymmetric transmission is also discussed.     

关于介质中光子动量的探讨

分析对于光从真空进入介质动量如何变化的问题的几个典型观点及存在的错误,由光的波粒二象性和光子与电子相互作用的机制,认识光在介质中传播时光子与光波的关系,得到介质中光子的动量仍等于它在真空中的动量.     

单模光场与级联三能级原子相互作用系统中熵的时间演化

研究了单模光场与级联三能级原子相互作用系统中,原子线性熵随时间的演化规律.讨论了光场的初态和失谐量对原子线性熵的影响.     

Fractional Angular Momentum of an Atom on a Noncommutative Plane

The mechanism of obtaining the fractional angular momentum by employing a trapped atom which possesses a permanent magnetic dipole moment in the background of two electric fields is reconsidered by using an alternative method. Then, we generalize this model to a noncommutative plane. We show that there are two different mechanisms,which include cooling down the atom to the negligibly small kinetic energy and modulating the density of electric charges to the critical value to get the fractional angular momentum theoretically.     

Photon Gas Thermodynamics in Noncommutative Momentum Spaces

In this paper, we study thermodynamical properties of the extreme relativistic gases in canonical ensembles in non-commutative momentum spaces. In this regards, we exactly calculate the modified partition function, Helmholtz free energy, internal energy, entropy, heat capacity and the thermal pressure in the momentum spaces. Moreover, we conclude at high temperature limits due to the decreasing of the number of micro-states, these quantities reach to maximal bounds which do not exist in standard cases and it concludes that at the presence of gravity for both micro-canonical and canonical ensembles, the internal energy and the entropy tend to these upper bounds.

     

Continuous-Variable Entanglement Generation from a Four-State Atom under Raman Excitation

We investigate the generation and the evolution of continuous-variable (CV) entanglement from a laser-driven four-state atom inside a doubly resonant cavity under Raman excitation. Two transitions in the four-state atom independently interact with the two cavity modes, while two other transitions are driven by coupling laser fields. By including the atomic relaxation as well as cavity losses, we show that the CV entanglement with large mean number of
photons can be generated in our scheme. We also show that the intensity of the coupling laser fields can influence effectively the entanglement period of the cavity field. Different from the conventional resonant excitation scheme where zero one-photon detuning are required, it is found that the intensity and period of entanglement between the two cavity modes as well as the total mean photon number of the cavity field can be adjusted by properly
modulating the frequency detuning.     

通讯波段单光子探测器的研制

将InGaAs/InP雪崩光电二极管应用于盖革模式下,采用门脉冲模式淬灭雪崩,并使用魔T混合网络抑制尖峰噪声,实现了通信波段1550 nm的单光子探测.在APD工作温度为223 K时,测得暗计数率与探测效率的比值为0.035.     

Dephasing Process of a Single Atom Interacting with a Two-Mode Field

We consider the interaction of a qubit system with a two-mode field in the presence of multi-photon transition and phase damping effect. We use the master equation to obtain the density operator when the qubit is initially prepared in its excited state and the field is in a finite-dimensional pair coherent state. The properties of the considered system, such as the population inversion, amount of the mixedness, parameter estimation, and squeezing, are explored for one- and two-photon transitions. The effects of photon addition to the field and phase damping on the evaluation of these quantumness measures are also investigated.