Single photon transport properties in coupled cavity arrays nonlocally coupled to a two-level atom in the presence of dissipation

We discuss the effects of dissipation on the behavior of single photon transport in a system of coupled cavity arrays,with the two nearest cavities nonlocally coupled to a two-level atom.The single photon transmission amplitude is solved exactly by employing the quasi-boson picture.We investigate two different situations of local and nonlocal couplings,respectively.Comparing the dissipative case with the nondissipative one reveals that the dissipation of the system increases the middle dip and lowers the peak of the single photon transmission amplitudes,broadening the line width of the transport spectrum.It should be noted that the influence of the cavity dissipation to the single photon transport spectrum is asymmetric.By comparing the nonlocal coupling with the local one,one can find that the enhancement of the middle dip of single photon transmission amplitudes is mostly caused by the atom dissipation and that the reduced peak is mainly caused by the cavity dissipation,no matter whether it is a nonlocal or local coupling case.Whereas in the nonlocal coupling case,when the coupling strength gets stronger,the cavity dissipation has a greater effect on the single photon transport spectrum and the atom dissipation affection becomes weak,so it can be ignored.

Vacuum induced transparency and slow light phenomena in a two-level atomic ensemble controlled by a cavity

We study the optical properties of a two-level atomic ensemble controlled by a high-finesse cavity. Even though the cavity is initially in the vacuum state in the absence of external driving, the probe response of the atomic ensemble can be dramatically modified. When the collectively enhanced atom–cavity coupling is strong enough and the cavity decay rate is much smaller than the atomic damping rate, an electromagnetically induced transparency-like coherent phenomenon emerges with a dip absorption for the response of the two-level atoms in the cavity without driving, and thus is called vacuum induced transparency. We also show the slow light with very low group velocity in such an atomic ensemble.

Optimal entropy squeezing sudden generation and its control for an effective two-level moving atom entanglement with the two-mode coherent fields

From the viewpoint of quantum information, this paper proposes a concept and a definition of the atomic optimal entropy squeezing sudden generation (AOESSG) for the system of an effective two-level moving atom which entangles with the two-mode coherent fields. It also researches the relationship between the AOESSG and entanglement sudden death of the atom-fields, and discusses the influences of atomic initial state on the AOESSG and obtains the system parameter which controls the AOESSG.

Effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field

The effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field are investigated. It is shown that the time evolution of the atomic population is mainly controlled by the coupling constants and the frequency of the low frequency field, which leads to a low frequency modulation function for the time evolution of the upper state population. The amplitude of the modulation function becomes larger as the coupling constants increase. The frequency of the modulation function is proportional to the frequency of the low frequency field, and decreases with increasing coupling constant.

The breaking point between fast-and slow-light in a degenerate two-level atomic system

This paper investigates the breaking point between fast-and slow-light in a degenerate two-level atomic system,where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field.An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature.The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.

Entanglement of two-level atoms' quantum states in a strong thermal radiation field

The two-level atom is described by Pauli sign and environment is described by infinite harmonic particle thermal reservoir.We have studied the entanglement of two-level atoms which are put in the strongly thermal radiation field.The two-level atoms' reducible density rectangular array is obtained.We discuss the properties of entanglement by virtue of concurrence.It is shown that the two two-level atoms initially situated in different coherent superposition states,entanglement of atoms have obvious dissimilarity.

The entanglement evolution of two coupling two-level atoms interacting with a single-mode vacuum field in multiphoton Tavis-Cummings model

Using multipohton Tavis-Cummings model,the entanglement evolution of two coupling two-level atoms in Bell states interacting with a single-mode vacuum field is investigated by using negativity.The influences of coupling constants between atoms,the atomic initial states and the photon number of transition on the entanglement evolution of two coupling two-level atoms are discussed.The results obtained using the numerical method show that the entanglement of two atoms is related with coupling constants between atoms,the atomic initial states and the photon number of transition.The two-atom entanglement state will forever stay in the maximum entanglement state when the initial state is β11〉.When the initial state of two atoms is β01〉,the entanglement of two atoms displays periodic oscillation behavior.And its oscillation period decreases with increasing of coupling constant between atoms or the photon number of transition.On the other hand,when the initial state is β00〉 or β10〉,the entanglement of two atoms displays quasiperiodic oscillation behavior and its oscillation period decreases with increasing of coupling constant between atoms or the photon number of transition.

Production of Entanglement of Multiple Three-Level Atoms with a Two-Mode Cavity

一个计划被建议因为产生纠缠的格言联盟者为二或更说三水平的原子。在计划，原子一个一个地是通过一个二模式的洞的位子并且顺序与二洞的模式交往。要求的试验性的技术在能在微波洞证完安装被获得的范围以内。

Quantum Fisher Information of Two-Level Atomic System under the Influence of Thermal Field, Intrinsic Decoherence, Stark Effect and Kerr-Like Medium

In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.

The Pancharatnam Phase of a Three-Level Atom Coupled to Two Systems of N-Two Level Atoms

In this paper, we present the analytical solution for the model that describes the interaction between a three-level atom and two systems of N-two level atoms. The effects of the quantum numbers and the coupling parameters between spins on the Pancharatnam phase and the atomic inversion, for some special cases of the initial states, are investigated. The comparison between the two effects shows that the analytic results are well consistent.

Two-dimensional atom localization via probe absorption in a four-level atomic system

We have investigated the two-dimensional (2D) atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.

The squeezing dynamics of two independent atoms by detuning in two non-Markovian environments

The squeezing dynamics of two independent two-level atoms off-resonantly coupled to two non-Markovian reservoirs is studied by the time-convolutionless master-equation approach. We find that the squeezing of two atoms is dependent on both detuning and the non-Markovian effect. Our results show that, in the non-Markovian regime, the bigger the detuning and the stronger the non-Markovian effect are, the larger the strength of the squeezing is. And the squeezing of two atoms can be effectively protected for a long time when both the non-Markovian effect and detuning are present simultaneously. The physical mechanism is that the detuning not only can promote the feedback of information from the environment into the atomic system but also can greatly suppress the atomic decay in the non-Markovian regime.

Influence of selective atomic measurement on the entanglement properties of a two-atom outside cavity

Considering three two-level atoms initially in the W or Greenberger-Horne-Zeilinger(GHZ) state,one of the three atoms is put into an initially coherent light cavity and made to resonantly interact with the cavity.The twoatom entanglement evolution outside the cavity is investigated.The influences of state-selective measurement of the atom inside the cavity and strength of the light field on the two-atom entanglement evolution outside the cavity are discussed.The results obtained from the numerical method show that the two-atom entanglement outside the cavity is strengthened through state-selective measurement of the atom inside the cavity.In addition,the strength of the light field also influences the two-atom entanglement properties.

Entropy of Field Interacting With Two Atoms in Bell State

在这篇论文，我们调查开始处于四个贝尔状态之一与二个二水平的原子交往的单个模式的协调的光地的熵性质。二个原子的不同起始的状态导致地熵的不同进化，这被发现，这块地的紧张为地熵的进化性质起一个重要作用。

Effect of cavity dissipation on the emission spectrum of an atom interacting with a field in the dispersive approximation

The emission spectrum of a two-level atom interacting dispersively with a single mode radiation field in the dissipative cavity is investigated. A general expression for the emission spectrum is derived. The numerical results for the initial field in coherent state are calculated. It is found that the spectrum structure is influenced significantly by the cavity damping constant κ, and the spectrum structure is dependent on the interaction time T when the cavity dissipation is present. Only one peak located at ω a appears in the atomic spectra for larger T.

Temperature dependence of the energy-level shift induced by the Bose-Einstein condensation of photons

We investigate the energy-level shift of a hydrogen atom in a two-dimensional optical microcavity, where there exists a Bose-Einstein condensation of photons. It is found that below the critical temperature T c , the energy-level shift of the bound electron is dependent on temperature, and it is a monotonically increasing function of the absolute temperature T . Especially, at the absolute zero temperature, the energy-level shift entirely comes from the Lamb shift, and the atom can be treated approximately, that is, in vacuum.

Spin Accumulation of Spinor Atoms in Optical Lattices

我们获得与一个二水平的原子描述光的相互作用的有效旋转关联 Hamiltonian，然后，我们由海森堡方程的数字集成调查 thetwo 水平原子系统的古典轨道打手势。只要旋转人物不能在 Hamiltonian 被忽视，我们的结果证明旋转累积是很流行的现象。我们建议试验性的协议在进一步的实验观察这新现象。

Efficient Atomic One-Qubit Phase Gate Realized by a Cavity QED and Identical Atoms System

我们在场与穿过一些相同原子在被套住的一个光洞的一个二水平的原子实现一扇 one-qubit 阶段门的一个计划。一个人能方便地由适当地选择在洞和穿过洞的原子的速度套住的原子的数字获得门的任意的阶段移动。现在的计划为实现 one-qubit 阶段门提供一个很简单、有效的方法。