基于量子隐形传态的量子保密通信方案

量子保密通信包括量子密钥分发、量子安全直接通信和量子秘密共享等主要形式.在量子密钥分发和秘密共享中,传输的是随机数而不是信息,要再经过一次经典通信才能完成信息的传输.在量子信道直接传输信息的量子通信形式是量子安全直接通信.基于量子隐形传态的量子通信(简称量子隐形传态通信)是否属于量子安全直接通信尚需解释.构造了一个量子隐形传态通信方案,给出了具体的操作步骤.与一般的量子隐形传态不同,量子隐形传态通信所传输的量子态是计算基矢态,大大简化了贝尔基测量和单粒子操作.分析结果表明,量子隐形传态通信等价于包含了全用型量子密钥分发和经典通信的复合过程,不是量子安全直接通信,其传输受到中间介质和距离的影响,所以不比量子密钥分发更有优势.将该方案与量子密钥分发、量子安全直接通信和经典一次性便笺密码方案进行对比,通过几个通信参数的比较给出各个方案的特点,还特别讨论了各方案在空间量子通信方面的特点.     

用一个纠缠态实现多粒子纠缠态的量子隐形传送

提出分别在二维和高维系统中利用一个纠缠态作量子通道实现M粒子纠缠态的量子隐形传送方案. 该方案有多个接收者,通过控制引进辅助粒子数,可以任意调节传送后的纠缠态在各接收者之间的粒子数分布, 且成功传送的概率为1. 关键词： 量子隐形传态 纠缠态 量子通道     

单光子纠缠态的纠缠转移和量子隐形传态

使用光学分束器和单光子源,利用单光子态和真空态制备出了纠缠单光子态.利用光学分束器作用和单光子探测,实现了三个通讯伙伴之间的纠缠转移.提出了一个关于纠缠单光子态的量子隐形传态方案.在这个方案中,被传送的是一个未知的单光子纠缠态.通讯双方使用的量子信道是两个单光子纠缠态.通过使用分束器作用和对输出态进行光子测量以及在经典信息的帮助下,纠缠转移和量子隐形传态的过程被完成.     

纠缠相干态的量子隐形传态

提出利用双模纠缠相干态作为量子信道，实现纠缠相干态量子隐形传态的方案. 分别在非正交的相干态表象和另一个由相干态构成的正交态表象对双模纠缠相干态的隐形传态进行具体分析. 发现在相干态表象，虽然只要线性光学元件就可以完成隐形传态，但成功的概率小于1/2，而在正交态表象，只要能分辨4个由相干态构成的Bell态，成功的概率就是1. 关键词： 隐形传态 纠缠相干态 纠缠相干态量子信道     

一种基于纠缠态的量子中继通信系统

提出了一种基于纠缠态的量子中继通信系统,该系统应用纠缠为基本资源.纠缠为量子隐形传态和绝对安全的量子通信提供了保证.量子中继器用来延长高纠缠度的纠缠光子对的纠缠距离,利用纠缠交换和纠缠纯化在系统的发信者与受信者之间建立光子对的纠缠.应用量子隐形传态的原理传输量子信息.系统分析表明,量子通信系统的吞吐率随着通信双方成功建立纠缠的概率增大而显著增加,量子信号的传输距离取决于量子中继节点的级数.     

陆地量子移动通信最优纠缠多址中继方案

为了解决EPR纠缠通过大气空间在通信终端之间的分发问题,使量子移动用户之间及时建立纠缠,提出了一种新的陆地量子移动通信网络的量子纠缠多址中继方案和分区服务模型.分析比较了基于量子受控非门和极化分束器的两种纠缠纯化方法.结果表明:即使在量子移动终端之间没有共享EPR纠缠对的情况下,通过纠缠纯化和量子多址中继,仍然可以完成...     

量子纠缠和贝尔不等式及其在量子信息处理中的应用

1964年,爱尔兰数学家约翰·贝尔(John Bell)根据隐变量理论推导出了2个粒子系统的测量结果应该满足的不等式关系和所涉及的测量基本逻辑.法国科学家阿兰·阿斯佩(Alain Aspect)、美国科学家约翰·克劳泽(John Clauser)和奥地利科学家安东·蔡林格(Anton Zeilinger)分别从实验上证伪了该不等式.贝尔不等式的证伪宣告了隐变量理论的终结,展示了量子纠缠的奇特性质.为表彰他们在“纠缠光子实验、验证违反贝尔不等式和开创量子信息科学”方面所做出的贡献,瑞典皇家科学院将2022年诺贝尔物理学奖授予这3位科学家.本文概述了量子纠缠的概念和贝尔不等式的推导,介绍了2022年诺贝尔物理学奖获得者的代表性研究工作,并展示了量子技术的可能应用.     

量子信息中纠缠态所处的角色

简要给出了量子纠缠态的概念,评述了纠缠态在量子信息论中所处的角色,尤其说明了怎样用它来实现安全的通信。     

划时代的量子通信——写给世界第一颗量子科学实验卫星“墨子号”

量子通信领域的主要两个研究方向,一个是为经典信息传输做量子加密的“量子密钥分发”,另一个是利用量子纠缠传输量子比特的“量子远程(隐形)传态”。文章以“墨子号”量子科学实验卫星的实验任务为线索,首先讲述量子密钥分发中的BB84协议的原理和应用,并系统性介绍量子比特、量子不可克隆定理、量子纠缠、贝尔不等式等概念,以及量子远程(隐形)传态的原理。文末简要介绍“墨子号”量子科学实验卫星和配套地面站的系统构成,以及空间量子通信的发展趋势。     

利用三粒子纠缠态建立量子隐形传态网络的探讨

利用W态纠缠源可以产生三纠缠粒子，用这些相互纠缠的粒子作为量子信道，再辅以经典信道传送Bell基联合测量信息和von Neumann测量信息，便可实现量子隐形传态网络.基于上述思想，研究了三纠缠粒子量子隐形传态网络的物理基础，得到了基于三粒子W 关键词： 量子通信 量子隐形传态 W态')" href="#">W态     

一台用于空间状态模拟的紧凑型质子源

A compact proton beam source for space simulation has been developed.A compact structure was designed in order to meet the special requirements of miniaturization.Some particular means have been adopted for improving the proton portion and beam transmission at a long distance.The experimental results showed that 8mA/30keV proton beam can be successfully obtained from this source at about 700W input microwave power.     

Phase Space Bounds for Quantum Mechanics on a Compact Lie Group

Let K be a compact, connected Lie group and its complexification. I consider the Hilbert space of holomorphic functions introduced in [H1], where the parameter t is to be interpreted as Planck's constant. In light of [L-S], the complex group may be identified canonically with the cotangent bundle of K. Using this identification I associate to each a “phase space probability density”. The main result of this paper is Theorem 1, which provides an upper bound on this density which holds uniformly over all F and all points in phase space. Specifically, the phase space probability density is at most , where and a _t is a constant which tends to one exponentially fast as t tends to zero. At least for small t, this bound cannot be significantly improved. With t regarded as Planck's constant, the quantity is precisely what is expected on physical grounds. Theorem 1 should be interpreted as a form of the Heisenberg uncertainty principle for K, that is, a limit on the concentration of states in phase space. The theorem supports the interpretation of the Hilbert space as the phase space representation of quantum mechanics for a particle with configuration space K. The phase space bound is deduced from very sharp pointwise bounds on functions in (Theorem 2). The proofs rely on precise calculations involving the heat kernel on K and the heat kernel on . Received: 9 July 1996/Accepted: 9 September 1996     

Quantum Random Walk Approximation on Locally Compact Quantum Groups

A natural scheme is established for the approximation of quantum Lévy processes on locally compact quantum groups by quantum random walks. We work in the somewhat broader context of discrete approximations of completely positive quantum stochastic convolution cocycles on C*-bialgebras.     

Uniqueness Problem for Quantum Lattice Systems with Compact Spins

Quantum lattice systems with compact spins and nearest-neighbour interactions are considered. Uniqueness of the corresponding Euclidean Gibbs states is proved uniformly with respect to the temperature, in the case where the particles have a sufficiently small mass.     

Quantum Coherence and Bose-Einstein Correlations for Time-Dependent Source

Bose-Einstein correlation (BEC) is appropriate conditions quantum coherence which is between two or more bosons. In this paper, we study the coherence of two-boson in accelerating and decelerating expansion source. The two-boson momentum correlation function is given by quantum statistics methods. The conclusion is that the momentum correlation function is a sensitive function of several parameters which includes particles’ momentum, the temperatures and evolution time of system.     

On Quantum Mechanics on Noncommutative Quantum Phase Space

In this work, we develop a general framework in which Noncommutative Quantum Mechanics (NCQM), characterized by a space noncommutativity matrix parameter θ=ε_ij^k θ_k and a momentum noncommutativity matrix parameter β=ε_ij^k β_k, is shown to be equivalent to Quantum Mechanics (QM) on a suitable transformed Quantum Phase Space (QPS). Imposing some constraints on this particular transformation, we firstly find that the product of the two parameters θ and β possesses a lower bound in direct relation with Heisenberg incertitude relations, and secondly that the two parameters are equivalent but with opposite sign, up to a dimension factor depending on the physical system under study. This means that noncommutativity is represented by a unique parameter which may play the role of a fundamental constant characterizing the whole NCQPS. Within our framework, we treat some physical systems on NCQPS : free particle, harmonic oscillator, system of two-charged particles, Hydrogen atom. Among the obtained results, we discover a new phenomenon which consists of a free particle on NCQPS viewed as equivalent to a harmonic oscillator with Larmor frequency depending on β, representing the same particle in presence of a magnetic field $\vec{B}=q^{-1}\vec{\beta}$. For the other examples, additional correction terms depending on β appear in the expression of the energy spectrum. Finally, in the two-particle system case, we emphasize the fact that for two opposite charges noncommutativity is effectively feeled with opposite sign.     

紧凑型LED配光设计中光源模型可靠性研究

针对现有LED光源建模适用条件及可靠性不确定性的问题,对紧凑型LED配光设计中光源建模可靠性进行了研究.通过优化设计具有不同透镜光源直径比模型的方法,对点光源、表面光源、ray文件光源三种建模方式在系统中的差异进行分析对比.整体设计以ray文件光源模型为基准,以常规紧凑型全反射式透镜为二次配光元件,对不同透镜光源直径比(光束角分别为±15°、±10°、±5°)的光学系统进行优化设计和分析计算.结果表明:在能量利用率误差为±2%的范围内,光束角为±15°,透镜光源直径比大于36∶2时,表面光源建模可代替ray文件光源建模;光束角±10°,透镜光源直径比为44∶2时,表面光源建模可代替ray光源建模;光束角为±5°,透镜光源直径比为82∶2时,表面光源建模可代替ray文件光源建模.但是在±2%误差范围内,点光源无论在何种透镜光源直径比,任何光束角下均不能代替ray文件光源.这一结果为紧凑型系统设计中光源模拟提供了依据,同时解决了采用ray文件光源建模进行辅助优化设计耗时较长的问题,为相关研究提供了参照依据.