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1.
Emission Spectrum from Two Atoms in Bell States in a Cavity 总被引:5,自引:0,他引:5
1 Introduction Inrecentyears ,therehasbeenmuchinterestinentangledstatesbecauseofthedevelopmentof quantuminformation .Entanglementisoneofthemoststrikingfeaturesofquantummechanics .Anentangledstate ,as generallydefined ,cannotbeseparatedintoaproductofthesta… 相似文献
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A protocol for complete and nondestructive atomic Bell‐state analysis by using inverse engineering is presented. The setups for the Bell‐state analysis contain four atoms trapped in four separated cavities, respectively. The laser pulses designed by inverse engineering help in the manipulation of the transitions of atoms in a robust manner. By using the protocol, the information for distinguishing four Bell states of two information‐carrying atoms is encoded on two auxiliary atoms. Therefore, the four Bell states can be distinguished without being destroyed by detecting the states of the two auxiliary atoms. Moreover, as shown by the numerical simulations, the protocol has high successful probabilities to distinguish four Bell states when decoherence is considered. Thus, the protocol may provide some helpful perspectives for the quantum information tasks based on Bell states. 相似文献
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与两等同Bell态纠缠原子相互作用光场的量子场熵 总被引:2,自引:1,他引:1
利用全量子理论,并通过数值计算,研究了初始处于Fock态的单模光场与两等同双能级纠缠原子单光子共振相互作用过程中单模光场量子场熵的时间演化特性.结果发现:当两原子初始处于第一种Bell态时,光场量子场熵的时间演化周期为π/g2(2n+1);随着初始光强的增大,光场与原子之间的量子纠缠现象减弱;特别是当时间t为演化周期的整数倍时,场-原子系统处于退纠缠状态.当两原子初始处于第二种Bell态时,光场量子场熵不随时间变化,恒为零.当两原子初始分别处于第三种和第四种Bell态时,光场量子场熵的时间演化曲线呈现不等幅周期振荡现象;并且随着初始光场光子数的增加,光场量子场熵的振荡周期逐渐增大,但振荡幅值逐渐减小. 相似文献
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F. Casagrande A. Lulli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):165-172
We investigate the entanglement of an open tripartite
system where a cavity field mode in thermal equilibrium is
off-resonantly coupled with two atoms that are simultaneously driven
by a resonant coherent field. For moderately detuned atom-field
coupling and strong atomic driving we show the generation, at given
interaction times and for low enough cavity decay rates, of atomic
Bell states and of Bell state superpositions relevant for quantum
gates implementation. The system can oscillate between bi-separable
and fully separable states. Also we describe the distribution of
quantum correlations between the atom-atom and the two atom-field
subsystems. In the dispersive coupling regime with strongly driven
atoms we show the generation of nearly stationary Bell states which
remain protected from cavity dissipation. 相似文献
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考虑原子间偶极相互作用,求出好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度。结果表明,对于理想腔,若原子初始时刻处于相干保持态,系统保真度始终等于1;若原子初始时刻处于其余Bell态之一,腔场初态的平均光子数很小,系统保真度在0~1之间作周期性振荡,随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小。对于好腔,若原子初始时刻处于相干保持态,系统保真度呈指数单调衰减;若原子初始时刻处于其余Bell态之一,系统保真度呈指数振荡衰减,且随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小。 相似文献
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好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度 总被引:2,自引:2,他引:0
考虑原子间偶极相互作用,求出好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度.结果表明,对于理想腔,若原子初始时刻处于相干保持态,系统保真度始终等于1;若原子初始时刻处于其余Bell态之一.腔场初态的平均光子数很小,系统保真度在0~1之间作周期性振荡,随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小.对于好腔,若原子初始时刻处于相干保持态,系统保真度呈指数单调衰减;若原子初始时刻处于其余Bell态之一,系统保真度呈指数振荡衰减,且随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小. 相似文献
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Y. Q. Zhang L. Tan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):585-592
Entanglement, purity and energy of two isolated two-level atoms which are initially prepared in Bell state and each interacts with a dissipative thermal cavity field are investigated with considering the atomic motion and the field-mode structure. We give the analytical solution of the atomic state by using the algebraic dynamics approach. The influences of the field-mode structure, the dissipation of the cavities, the strength of the thermal field and the detuning on the entanglement, purity and energy are discussed. We also study the evolution of the atomic state using the entanglement-purity-energy diagrams. Our results suggest that the disentanglement process of the atomic state accompanies with the excitations transferring from atoms to the cavity field modes and with the state converting from a pure one to the mixed ones. When the two atoms become separable, they must be in the mixed states, and their energy decreases with the increase of the purity. 相似文献
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研究了双模腔场中两个偶极相互作用原子的辐射谱,详细讨论了双模腔场分别处于不同数态时的情形,发现其辐射谱具有如下特点:当两模腔场均处于真空态时,随着δ=ga/g的增加,辐射谱交替出现六峰、五峰结构,且在δ(=3-1/2)很小时就出现了非对称五峰结构,与单模双原子情形相比较,更为灵敏地反映出原子间的偶极相互作用;当一腔场为真空场,另一腔场为强场时,辐射谱显示出对称的六峰结构,任意两对称峰的间距与(2n2)1/2g成正比;当
关键词: 相似文献
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Bell态原子与双模纠缠相干光场相互作用的纠缠特性 总被引:1,自引:0,他引:1
运用Negativity熵研究了Bell态原子与双模纠缠相干光场相互作用系统中两个全同二能级原子之间的纠缠演化特性.分析了光场强度、光场纠缠度及原子间相互作用强度对纠缠的影响.结果表明:原子处于|β11〉时,两原子始终处于最大纠缠态;原子处于|β00〉时,初始纠缠的两原子始终较长时间处于退纠缠状态;原子处在|β10〉时,增大双模光场的平均光子数可以明显增大两原子之间的纠缠度并保持较大的纠缠状态;原子初态处在|β01〉时,原子间的相互作用强度对双原子间纠缠度有较显著的非线性调制作用. 相似文献
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运用全量子理论并结合数值计算方法,研究了处于Bell态的两个全同二能级纠缠原子与双模纠缠相干光场相互作用系统的光子统计性质.分析了双原子体系的初态、光场的平均光子数、双模纠缠相干光场的纠缠程度以及双原子体系的原子间耦合强度对双模光场的光子统计性质的影响.结果表明:双原子体系的初态为|β00〉、|β10〉时,光场在其演化过程中不出现光子的反聚束效应;而当原子初态为|β01〉或|β11〉时,在一定的条件下可出现光子的反聚束效应.并且在光场的演化过程中,光子的反聚束效应出现的次数、时间和深度极其敏感地依赖于初始光场的平均光子数,而受到双模纠缠光场的纠缠程度以及双原子间偶极作用强度的影响很微弱. 相似文献
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A scheme is proposed to simulate the Ising model and preserve the maximum entangled states (Bell states) in cavity quantum
electrodynamics (QED) driven by a classical field with large detuning. In the strong driving and large-detuning regime, the
effective Hamiltonian of the system is the same as the standard Ising model, and the scheme can also make the initial four
Bell states of two atoms at the maximum entanglement all the time. So it is a simple memory for the maximal entangled states.
The system is insensitive to the cavity decay and the thermal field and more immune to decoherence. These advantages can warrant
the experimental feasibility of the current scheme. Furthermore, the genuine four-atom entanglement may be acquired via two
Bell states through one-step implementation on four two-level atoms in the strong-driven model, and when two Greenberger-Horne-Zeilinger
(GHZ) states are prepared in our scheme, the entangled cluster state may be acquired easily. The success probability for the
scheme is 1.
Supported by the National Natural Science Foundation of China (Grant No. 10774088) and the Key Program of the National Natural
Science Foundation of China (Grant No. 10534030) 相似文献
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We use quantum field entropy to measure the degree of entanglement for a coherent state light field interacting with two atoms that are initially in an arbitrary two-qubit state. The influence of different mean photon number of the coherent field on the entropy of the field is discussed in detail when the two atoms are initially in one superposition state of the Bell states. The results show that the mean photon number of the light field can regulate the quantum entanglement between the atoms and light field. 相似文献
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Λ-型三能级单原子的辐射谱 总被引:5,自引:0,他引:5
采用时间演化算符方法,研究腔内单模光场中Λ-型三能级单原子的辐射谱,给出了辐射谱一般公式,并讨论在粒子数纯态、相干态和热辐射三种光场激励下的辐射频谱结构。 相似文献
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两原子与双模腔场的多光子喇曼相互作用 总被引:2,自引:1,他引:1
研究了两个等同有效二能级原子与双模腔场的多光子喇曼相互作用,导出了双模腔场处于任意态时,该系统中两原子辐射谱的一般表达式,并分析了辐射谱的特点。 相似文献
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含Kerr介质的Fock态和相干态腔场中耦合双原子辐射谱 总被引:3,自引:3,他引:0
研究了在充满Kerr介质的高Q腔中两个具有偶极-偶极相互作用的二能级原子辐射谱,给出了初始光场为Fock态和相干态时辐射谱的数值结果.讨论了Kerr效应对谱结构的影响.在初始注入光场为较强的相干态时,辐射谱除中心单峰外,两侧各出现一个多峰梳状边带,峰的个数随初始场平均光子数-n的增大而增多,峰间距随Kerr介质与光场的耦合系数X的增大而增大,两个边带则随Xn-的增大逐渐远离. 相似文献
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SHAN Chuan-Jia CHENG Wei-Wen LIU Tang-Kun GUO De-Jun XIA Yun-Jie 《理论物理通讯》2008,49(6):1505-1514
Considering the dipole-dipole coupling intensity between two atoms and the field in the Fock state, the entanglement dynamics between two atoms that are initially entangled in the system of two two-level atoms coupled to a single mode cavity in the presence of phase decoherence has been investigated. The two-atom entanglement appears with periodicity without considering phase decoherence, however, the phase decoherence causes the decay of entanglement between two atoms, with the increasing of the phase decoherence coefficient, the entanglement will quickly become a constant value, which is affected by the two-atom initial state. Meanwhile the two-atom quantum state will forever stay in the maximal entangled state when the initial state is proper even in the presence of phase decoherence. On the other hand, the Bell violation and the entanglement do not satisfy the monotonous relation, a large Bell violation implies the presence of a large amount of entanglement under certain conditions, while a large Bell violation corresponds to a little amount of entanglement in certain situations. However, the violation of Bell-CHSH inequality can reach the maximal value if two atoms are in the maximal entangled state, or vice versa. 相似文献