共查询到20条相似文献,搜索用时 125 毫秒
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增加光子对和减少光子对相干态的统计性质 总被引:15,自引:3,他引:12
引入增加光子对相干态|ζ,q;m >a=a+m|ζ,q >和减少光子对相干态|ζ,q;-m >b=bm|ζ,q >,研究了这些态所描写的光场的统计性质。结果显示当在对相干态的a模增加光子时,两模的平均光子数均增加,亚泊松分布性质增强;当在对相干态的b模取走光子时,b模的平均光子数减少,而a模的平均光子数却增加;b模的亚泊松分布性质减弱,而a模的亚泊松分布性质却增强。我们还计算了场模间的相关度和场模的压缩。 相似文献
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增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备 总被引:2,自引:1,他引:1
分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备. 相似文献
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卢道明 《原子与分子物理学报》2009,26(1):119-124
利用Tavis-Cummings模型研究了耦合二能级原子通过多光子跃迁与相干态光场相互作用系统中场熵的演化规律,讨论了原子间耦合强度和光场初始平均光子数的变化对场熵演化的影响。数值计算结果表明: 场熵的演化受原子间耦合强度和光场初始平均光子数的变化的影响.随光场初始平均光子数的增大,场熵平均值增大。 相似文献
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光子增加混沌场的退相干和非经典效应 总被引:1,自引:0,他引:1
将产生算符作用在混沌场上,构造了光子增加混沌场.利用有序算符内的积分技术和热纠缠态表象求解密度矩阵主方程的方法,研究了振幅衰减模型中光子增加混沌场的退相干和非经典效应.通过解振幅衰减模型中的密度算符的主方程,得到了初态为光子增加混沌场的密度算符的演化公式.计算了终态密度算符的P表示和Wigner函数,并数值计算了耗散对其P表示和Wigner函数的影响.结果表明:随耗散时间的增长,光子增加混沌场的非经典效应减弱.另一方面,随光子增加数的增加,其非经典效应也减弱. 相似文献
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双模SU(1,1)相干态场与原子相互作用过程的场熵演化 总被引:3,自引:3,他引:0
研究子双模SU(1,1)相干态场与二能级原子相线作用过程中场熵的演化特性,分析了双模光子数差,原子相干性及失谱量对场熵演化的影响。 相似文献
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卢道明 《原子与分子物理学报》2010,27(1):113-116
利用时间演化算符方法研究了K模相干光场与二能级原子相互作用系统中系统态矢的演化.利用数值计算方法研究了三模相干光场与二能级原子相互作用系统中场熵的演化,讨论了初始光场强度对场熵演化的影响.结果表明:当初始光场较强时,场熵随时间的演化呈现出规则的振荡,光场与原子之间的相互作用主要表现为双光子跃迁过程. 相似文献
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We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state. 相似文献
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ZOU Jian CAI Jin-Fang SHAO Bin LI Qian-Shu 《理论物理通讯》2005,44(2):259-268
We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state. 相似文献
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The entanglement of two atomic qubits, which are coupled to a coherent state field with different couplings, is studied. The dynamical evolution of the concurrence, which measures the degree of the entanglement between the two qubits, is plotted versus the scaled
time gt. It is found that the two qubits can be entangled by the coherent state field even when they are initially prepared in the most mixed state, and for very weak field, the most mixed state can be more easily entangled than some pure
states. It is also found that the entanglement between the qubits sensitively depends on the relative difference of the atomic couplings and the mean photon number of the field. 相似文献
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纠缠双原子和相干光场作用的光子统计非经典特性 总被引:2,自引:0,他引:2
采用数值计算法研究了纠缠双原子和相干光场相互作用中辐射光场光子数分布的演化特性。结果表明,通过和纠缠双原子的相互作用,使得不具有反聚束效应和光子亚泊松分布的相干光场获得了非经典特性。并且初始双原子间的纠缠强度越大,辐射光场的非经典性质越强,说明可以通过选择初始原子状态制备非经典辐射光场。 相似文献
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Humio Inaba 《Optical Review》1997,4(1):A1-A10
In advanced sensing photonics it is of great importance to explore the detection limits of extremely weak optical signals
and imaging using state-of-the art technology. In this paper we describe recent progress in photonic sensing technology achieved
in practice in the standard quantum limit of optical detection imposed by the signal-limited shot noise, which can be realized
by both the optical heterodyne detection and photon counting techniques. Then, with particular attention on imaging of ultraweak
photonic signals by these techniques, their applications in developing new frontiers in the field of biophotonics such as
laser computed tomography, and the imaging and characterization of ultraweak biophoton emission phenomena are described and
discussed as one of the typical examples of future trends in this field. 相似文献
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Entropy evolvement properties in a system of Schrodinger cat state light field interacting with two entangled atoms
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The field entropy can be regarded as a measurement of the degree of
entanglement between the light field and the atoms of a system which is
composed of two-level atoms initially in an entangled state interacting with the Schr\"{o}dinger cat state. The influences of the strength of light field and the phase angle between the two coherent states on the field entropy are discussed by using numerical calculations. The result shows that when the strength of light field is large enough the field entropy is not zero and the degrees of entanglement between the atoms and the three different states of the light fields are equal. When the strength of the light field is small, the degree of entanglement is maximum in a system of the two entangled atoms interacting with an odd coherent state; it is intermediate for a system of the two entangled atoms interacting with the Yurke--Stoler coherent state, and it is minimum in a system of the two entangled atoms interacting with an even coherent state. 相似文献
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运用全量子理论并结合数值计算方法,研究了克尔介质腔中处于贝尔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特性。讨论了双原子体系的初态、初始光场的平均光子数、双模纠缠相干光场的纠缠程度以及克尔介质与双模光场的耦合强度对光子统计特性的影响。结果表明:忽略克尔介质的作用时,只有当双原子体系的初态为0β1〉或1β1〉时,在一定的条件下才可出现光子的反聚束效应,而当双原子体系的初态为β00〉、1β0〉时,光场在其演化过程中不出现光子的反聚束效应。而当考虑克尔介质的作用时,四种初态下光场演化过程中均有可能出现光子的反聚束效应。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和克尔介质与双模光场的耦合强度,同时也受到双模纠缠光场的纠缠程度的影响。 相似文献
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三能级原子与奇偶纠缠相干光作用的光场压缩 总被引:8,自引:2,他引:6
采用求解薛定谔方程和数值计算方法,研究了V型三能级原子与双模奇偶纠缠相干光场相互作用过程中的光场压缩效应,讨论了压缩效应与双模奇偶纠缠相干光场的纠缠程度、系统失谐量、双模光场的平均光子数和原子基态概率幅的依赖关系。结果表明:光场压缩效应与双模奇偶纠缠相干光场的纠缠程度、失谐量、平均光子数和原子初态相关联:双模纠缠相干光场处于非纠缠状态时的光场压缩量比光场处于纠缠状态时要大;原子处在单纯的基态或激发态时光场都有明显的压缩现象出现;而原子初态中基态和激发态的概率幅较接近时无光场压缩现象;无论光场是否处于纠缠态,只有两模平均光子数接近时,光场才会出现压缩效应。 相似文献
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碱金属原子是光量子存储的良好介质,与碱金属原子共振的非经典光场是量子信息处理的重要资源.本文采用周期极化磷酸氧钛晶体作为非线性介质,利用参量振荡过程产生了795 nm(铷原子D1线)的真空压缩光场.通过对平衡零拍探测系统的时域信号进行采集,得到压缩光场不同相位角下的噪声分布;利用极大似然估计法对压缩光场进行了态重构,得到了密度矩阵及相空间的Wigner函数.理论计算了真空压缩场的光子数分布和Wigner函数,并对理论计算结果和极大似然重构结果进行了分析和比较. 相似文献