压缩态光场的四阶量子干涉

采用半经典理论讨论了同一抽运源抽运的两个独立光学参量振荡腔(OPO)所产生的压缩态光场的四阶量子干涉效应．结果表明：在OPO振荡阈值处,输出光场压缩度最高但四阶量子干涉最弱,条纹可见度为33.3%,远离阈值时干涉越来越强. 关键词：     

几类相干态的量子保真度

在坐标表象下,研究了几类相干态的量子保真度,对于相干态,我们给出了量子保真度的解析表达式,考查了谐振子特征长度 ,平移距离 对保真度的影响;对于相干态 与 的叠加态,考查了初态量子干涉对量子保真度的影响,结论表明：量子保真度呈周期性;与相干态的量子保真度比较而言,当谐振子处于第二类相干态时,量子干涉能抑制量子态失真,当谐振子处于第三类相干态时,量子干涉能抑制量子态失真,也可能加大量子态失真.     

振幅相干态的量子统计性质

对振幅相干态|ψ＞的非经典性质进行了研究，用数值计算的方法讨论了它的振幅压缩性质、亚泊松分布特性和反聚束效应。     

大气闪烁对纠缠相干态量子干涉雷达影响机理

介绍了量子干涉雷达物理模型及其探测原理,并采用耗散-涨落通道处理量子光场在湍流大气中的传输,从经典湍流统计理论推导得到大气透射率的概率密度分布函数P(T),以此为基础系统分析了大气闪烁效应对纠缠相干态量子干涉雷达的影响机理,深入讨论了平均大气透射率、闪烁指数等大气参数对系统目标探测性能的影响.研究发现:低损耗情况下系统灵敏度及分辨率性能随闪烁指数的增加而降低;高损耗情况下大气闪烁则能显著提高系统灵敏度和分辨率性能,且界定高低损耗的透射率临界点随脉冲光子数增加而增加,故大气闪烁能够在一定程度上克服大气损耗造成的不良影响.     

奇偶相干迭加态的振幅高次方压缩

本文引入了学子消灭算符四次方算符α＾４新的正交归一本征态：奇偶相干态和奇偶相干迭加态，并研究了奇偶相干迭加态的振幅高次方压缩特性。     

利用原子干涉方法来制备压缩相干迭加态

在文中我们提出了一种基于原子干涉的方法产生压缩相干迭加态，由此方法产生的迭加态的位相及权重因子均可控制。     

量子信道干涉

单个信道的性质可以用量子测量和量子层析技术等方法描述，但是仅仅单个信道的性质还不足以描述两个信道同时作用时的情况。J．Aberg告诉我们仅仅知道单个信道的信息并不足以帮助我们说明两个映射（一个信道的作用可以用一个映射来描述）同时作用时的情况。但是两个信道之间的干涉可以提供给我们单个信道描述中所没有的附加信息，即两个信道间的相干性质。因此，干涉测量可以用来提取量子层析技术所不能获得的信息。     

相干瞬态的量子干涉效应和Berry相位

利用解析方法描述了相干瞬态量子体系中不同类型的量子干涉效应,分别讨论了光学干涉与量子干涉所起的作用,分析了在时域对称光场作用下,几何相位在量子干涉效应中所扮演的角色,从理论上证明了通过适当改变抽运场脉冲面积,可实现对几何相位的测量. 同时研究也发现利用啁啾抽运场可以实现对量子干涉效应的有效控制. 关键词： 相干瞬态 量子干涉 几何相位 啁啾脉冲     

经典干涉与量子干涉

 若将1609年伽利略使用望远镜观察月球作为以观察和实验为基础的现代物理学的起点,近400年来,科学技术获得了巨大的发展,经典物理学对宏观世界给出了几乎完美的描述,同时,由于科学技术的发展和人类认识水平的不断提高,经典物理的知识体系已远远不能满足人们认识世界的需要,随人们认识世界、改造世界的经验积累,20世纪物理学取得了两个划时代的发展--创立了相对论和量子力学,并使之分别成为认识高速、微观领域的利器。     

化学反应中的量子干涉

波长为157nm的 O2 在受激准分子激光器作用下可离解为 O3P 和 O1D .为了在理论上研究化学反应 的量子干涉效应,利用一阶含时波恩近似及各向异性相互作用势建立了量子干涉效应模型,讨论了完全干涉和完全非干涉两种情况。     

Measurement-Based Interference in Quantum Computation

The interference has been measured by the visibility in two-level systems,which,however,does not work for multi-level systems.We generalize a measure of the interference based on decoherence process,consistent with the visibility in qubit systems.By taking cluster states as examples,we show in the one-way quantum computation that the gate fidelity is proportional to the interference of the measured qubit and is inversely proportional to the interference of all register qubits.We also find that the interference increases with the number of the computing steps.So we conjecture that the interference may be the source of the speedup of the one-way quantum computation.     

远程控制光场的量子统计性质

考虑双模纠缠相干光场,将其中一束光场注入腔中与一个二能级原子发生共振相互作用,总系统在腔量子电动力学演化过程中,对原子作选择性的测量,通过操纵参加相互作用的时间以及选择适当的光场参量可控制未参加相互作用光场的量子统计性质,在一定条件下可产生反聚束、压缩态等非经典光场,并且通过适当的控制和调整这些参量可以改变未参加相互作用光场的反聚束和压缩特性的强弱。这样,通过利用腔与原子之间简单的共振相互作用和相干光场之间的纠缠关联,实现了远程的、无直接量子测量的控制或改变相干光场的非经典性质这一目的。     

Measurement-Based Interference in Quantum Computation

The interference has been measured by the visibility in two-level systems, which, however, does not work for multi-level systems. We generalize a measure of the interference based on decoherence process, consistent with the visibility in qubit systems. By taking cluster states as examples, we show in the one-way quantum computation that the gate fidelity is proportional to the interference of the measured qubit and is inversely proportional to the interference of all register qubits. We also find that the interference increases with the number of the computing steps. So we conjecture that the interference may be the source of the speedup of the one-way quantum computation.     

Interference in Phase Space of Squeezed States for the Time-Dependent Hamiltonian System

We showed that the idea of Schleich and Wheeler (1987, Nature 326, 574) for the semiclassical approach of the interference in phase space of harmonic oscillator squeezed states can be extended to that of general time-dependent Hamiltonian system. The quantum phase properties of squeezed states for the general time-dependent Hamiltonian system are investigated by using the quantum distribution function. The weighted overlaps A _n and phases θ _n for the system are evaluated in the semiclassical limit.     

Quantum Interference in Time

I discuss the interpretation of a recent experiment showing quantum interference in time. It is pointed out that the standard nonrelativistic quantum theory does not have the property of coherence in time, and hence cannot account for the results found. Therefore, this experiment has fundamental importance beyond the technical advances it represents. Some theoretical structures which consider the time as an observable, and thus could, in principle, have the required coherence in time, are discussed briefly, and the application of Floquet theory and the manifestly covariant quantum theory of Stueckelberg are treated in some detail. In particular, the latter is shown to account for the results in a simple and consistent way.     

量子信息光学

介绍了一门新的学科分支－量子信息光学。它是量子光学与信息科学相结合的产物。光场的量子效应在实现大容量的信息传输，超高精度的信息检测以及不可破译、不可窃听的量子密码术方面有着极其重要的应用前景，在光子学的发展中将发挥独特的作用。该文阐述了量子信息光学中若干物理问题和研究方向，包括超低噪声光源、量子信息复制、量子态工程、量子非破坏性测量和量子密码术。     

Gravitational Redshift Induces Quantum Interference

Quantum field theory in curved spacetime is used to show that gravitational redshift induces a unitary transformation on the quantum state of propagating photons. It is found that the transformation is a mode-mixing operation, and a protocol that exploits gravity to induce a Hong–Ou–Mandel-like interference effect on the state of two photons is devised. It is discussed how the results of this work can provide a demonstration of quantum field theory in curved spacetime.     

Interference in the Quantum Ising Model

Using the measure of interference defined in this paper, we investigate the quantum phase transition of one-dimensional Ising chains. We find that thermal fluctuations affect the interference more strongly at the critical point. We also show that the derivative of the interference with respect to the coupling parameter, A, can be depressed by the thermal fluctuation. Finally, we find that this suppression is due to multi-particle excitations.     

Collective Behavior in Quantum Interference: A Supplementary Superposition Principle

An interferometer in which all of its components are treated as quantum bodies is examined with the standard interpretation and with a model in which its uncoupled spatially separated components act collectively. These models utilize superposition principles that differ when applied to systems composed of three or more bodies. Interferometric discrepancies between these models that involve frequency shifts and recoil are shown to be difficult to measure. More pronounced differences involve quantum correlated interference. The collective model provides a missing connection between quantum and semiclassical theories. Scattering from an entangled state, which cannot be divided into disjoint parts, is proposed to involve such collective recoil. Collective scattering offers a viable supplement to the standard model, thereby providing insight into constructing tests of the superposition principle in systems with three or more bodies.     

基于双模压缩态的量子投票协议

提出了一种基于双模压缩态的基本量子投票协议,该协议通过随机选择信号加载的方式,充分利用量子信号测不确定性原理实现了分布式投票系统.并在此基础上分析可能遇到的攻击.双模压缩态的模间关联性保证了该方案的安全性. 关键词： 量子投票协议 双模压缩态 不确定性原理