Photons can hide where they have been

Recently,the nested Mach–Zehnder interferometer[Phys.Rev.Lett.111,240402(2013)]was modified by adding Dove prisms in a paper[Quantum Stud.:Math.Found.2,255(2015)],and an interesting result is that,after the Dove prisms were inserted,a signal at the first mirror of the nested interferometer was obtained.But,according to the former original paper,the photons have never been present near that mirror.In this work,we interpret this result naturally by resorting to the three-path interference method.Moreover,we find that even though the photons have been somewhere,they can hide the trace of being there.     

Entanglement Purification with Higher Error Threshold for Imperfection of Local Operations and Bell State Measurements

We analyse further the entanglement purification protocol proposed by Feng et al. [Phys. Lett. A 271(2000)44] in the case of imperfect local operations and measurements. It is found that this protocol allows of higher error threshold. Compared with the standard entanglement purification proposed by Bennett et al. [Phys. Rev.Lett. 76 (1996) 722], it turns out that this protocol is remarkably robust against the influences of imperfect local operations and measurements.     

压缩真空变态中二能级原子简并双光子过程的广义Bloch—Siegert频移

用密度算符主方程方法研究了一二能极原子与宽压缩真空态光场的简交双光子相互作用。我们发现原子偶极矩随时间的变化与压缩真空态光场的压缩参数│Ｍ│有关。│Ｍ│存在一个阈值Г／４ｇ。阈值之下，原子偶极矩以共振频率振荡。     

Scheme for Generation of Entanglement among Bimodal Cavities

We present a scheme for generation of an entangled state in many spatially separated bimodal cavity modes via cavity quantum electrodynamics. A V-type three-level atom, initially prepared in a coherent superposition of its excited states, successively passes through both the bimodal cavities. If the atom is measured in its ground state after leaving the last cavity, an entangled state of many cavity modes can be generated. The conditions to generate the maximally entangled state with unity probability are worked out.     

两能级原子在压缩真空态光场中双光子过程的细致平衡和熵的演化

利用细致平衡原理和熵的演化，研究了与压缩真空态光场进行简并双光子耦合的两能级系统的稳定性．发现当压缩真空态光场的压缩参数较小时，系统是不稳定的；而当压缩真空态光场的压缩参数为实数并且很大时，系统达到一种远离平衡态的稳定状态． 关键词：     

压缩真空库场中二能级原子的非简并双光子荧光谱

利用投影算符技巧从刘维方程出发导出了二能级原子约化密度算符主方程，研究了压缩真空库场中二能级原子的非简并双光子荧光谱特性.发现与真空库或热库中双光子荧光不同，在非简并双光子情况中存在一种新型振荡现象，它具有上下两个阈值，在上下阈值之间原子发生振荡，在两阈值之外原子将不发生振荡.在两阈值之间原子的非简并双光子荧光谱呈现正峰结构，在两阈值之外双光子荧光谱具有负的峰结构.光谱形状强烈地依赖于双光子自然线宽，但光谱是非相敏性的，这是未曾预料到的. 关键词：     

Improvement on controlled-controlled-NOT operation-based entanglement purification protocol

We show that controlled-controlled-NOT(CCN)operation-based entanglement purification protocol can be further improved.CCN protocol requires Bell state measurements after performing the CCN operations.In the original CCN protocol,the measured states are assumed to be destroyed.However,if controlled-NOT gates are used to perform such Bell state measurements,in some unsuccessful situations of the CCN protocol,one can further purify the two mixed entangled states which are to be measured.In this way,the total efficiency of the CCN protocol is further increased.     

压缩真空态光场抽运的双光子激光

利用激光全量子理论研究了压缩真空态光场抽运的双光子激光.讨论了双光子激光的阈值条件及其量子起伏,发现压缩真空态光场可以降低双光子激光的阈值,双光子激光场不具压缩效应 关键词：     

劣腔内二能级原子的双光子共振荧光光谱

研究了劣腔内二能级原子与单模腔场的双光子相互作用，腔内原子受外加固相干光场驱动，并向一般真空态自发辐射，通过腔镜内腔内注入压缩真空态光场，使腔模向压缩真空态光场衰减，本文利用劣腔近似条件得到原子约化密度算符主方程，在此基础上讨论了二能级原子的双光子共振荧光光谱。     

压缩真空场中非简并双光子过程中系统约化密度主方程

在本文中我们利用投影算符技巧通过刘维方程推导了系统约化密度主方程。这种方法特别适合于赝非马尔可夫的库场情况。所得结果和改进的路易塞尔方法的结果一致，这种方法能正确地在各种库的情况下给出单光子过程和双光子过程的系统的主方程，我们首次求得压缩真空库场中非简并双光子过程的系统约化密度主方程。