关于量子几何相位的评注——评三本量子力学教材中一个基本概念

回顾了国内出版的两本量子力学教材和一本参考书中有关贝里相位的章节，指出了其中有关量子几何相位的一些错误概念。     

运用"量子通则"时不应忽略的一个条件

“量子通则”是经典物理学向量子力学过渡中的“量子”条件 ,许多书中只强调周期性积分而忽略独立坐标的选择 .本文从一个简单问题论述了忽略独立坐标的要求将会产生错误 .值得在教学中注意     

从贝尔不等式到量子信息"热"

介绍了贝尔不等式的建立及20世纪70年代以来对它的实验验证．对贝尔不等式与量子力学基本解释的关系的深入研究,加速了“纠缠态”及其品性的发现,推动了量子信息“热”的兴起。     

有关A-B效应和相位问题及量子绝热定理成立条件——三答李华钟教授的评述

对《Aharonov-Bohm效应和量子力学相位概念的一些问题———评曾谨言著〈量子力学〉卷Ⅱ第六次印刷第四章的物理概念》一文中有关A-B效应和相位问题的评述,按真实情况给予了说明.论证了把R t→0作为量子绝热定理成立条件,不能说明“对于能级简并态,量子绝热定理不成立”,且在一些情况下会导致不正确的结论.     

量子力学相位因子

文章以电磁场为例说明规范场和相位因子的关系,说明相位因子何以是20世纪物理学的旋律之一,文章就目前文献或教材中流行着的一些量子力学相位概念作分析,指出必须区分清楚不可积相位和可积相位,文章还专门讨论了不可积相位的概念及其重要性。     

量子Berry相因子与相位教学

回顾了经典物理和量子力学中的相位问题,着重讨论了量子几何Berry相位及在量子力学中如何进行量子相位教学的问题.     

三维量子点的三电子系统

由量子力学对称性研究了三维量子点三电子系统的结构，指出了存在“幻数”的可能性，并与二维量子点三电子系统的“幻数”特征作了比较．在有效质量近似下，计算了抛物阱（?ω₀=2meV）三电子系统的能谱．结果表明在三维三电子量子点中存在“幻数”的迹象，但很少．理论分析和计算结果都表明三维量子点三电子系统的基态是1^-态 关键词：     

具有原子运动的双光子J-C模型中量子力学通道与量子互熵

用量子信息理论研究具有原子运动的双光子Jaynes_Cumming模型动力学.给出了该模型中表示原子态变化的量子力学通道，导出了量子互熵和原子约化熵，考察了原子运动及场模结构对量子互熵的影响，以及原子量子力学通道“开启”与“关闭”状态和原子与场纠缠程度的关系.结果表明量子力学通道特性强烈依赖于原子运动、场模结构以及原子与场的纠缠. 关键词： 双光子J_C模型 原子运动 量子互熵 量子约化熵 量子学通道     

量子力学年谱

年谱简要记载了从早期量子论诞生前后，到量子力学创立，直到量子力学的最新进展的重要科学事件的年代、有关科学家工作的内容和意义．     

我国科学家实现六光子薛定谔猫态

中国科技大学微尺度物质科学国家实验室潘建伟教授和同事杨涛、陆朝阳等，最近通过实验成功制备出国际上纠缠光子数最多的薛定谔猫态和可以直接用于量子计算的簇态，刷新光子纠缠和量子计算领域的两项世界纪录．该项研究成果以封面标题的形式发表在最新一期英国《自然》杂志的子刊《自然一物理》上．审稿人评价其是“光学量子计算领域至今最先进的实验工作”和“一个出色的成就，为量子计算、量子纠错和量子力学基本问题的研究铺平了道路”．     

Quantum Phase Properties of Photon Added and Subtracted Displaced Fock States

Quantum phase properties of photon added and subtracted displaced Fock states (and their limiting cases) are investigated from a number of perspectives, and it is shown that the quantum phase properties are dependent on the quantum state engineering operations performed. Specifically, the analytic expressions for quantum phase distributions and angular Q distribution as well as measures of quantum phase fluctuation and phase dispersion are obtained. The uniform phase distribution of the initial Fock states is observed to be transformed by the unitary operation (i.e., displacement operator) into non‐Gaussian shape, except for the initial vacuum state. It is observed that the phase distribution is symmetric with respect to the phase of the displacement parameter and becomes progressively narrower as its amplitude increases. The non‐unitary (photon addition/subtraction) operations make it even narrower in contrast to the Fock parameter, which leads to broadness. The photon subtraction is observed to be a more powerful quantum state engineering tool in comparison to the photon addition. Further, one of the quantum phase fluctuation parameters is found to reveal the existence of antibunching in both the engineered quantum states under consideration. Finally, the relevance of the engineered quantum states in the quantum phase estimation is also discussed.     

一种高效量子密钥分发系统主动相位补偿方法

针对相位编码量子密钥分发系统相位漂移的实际问题,详细分析了目前解决相位漂移的主要方案,提出了一种"五点法"快速相位漂移参数的扫描方法.该方法只需对五个相位点进行单光子水平的相位扫描,即可得出满足精度要求的相位漂移参数.通过将该方法和其他两种主要相位补偿方法的对比分析,表明该方法可以在更短的扫描时间内有效得到量子密钥分发的相位漂移参数并对相位漂移进行实时补偿.该方法适用于目前常用的相位编码系统,为量子密码系统提供了一种有实际应用价值的主动相位补偿方案.     

一维自旋1键交替XXZ链中的量子纠缠和临界指数

利用基于张量网络表示的矩阵乘积态算法以及无限虚时间演化块抽取方法,本文研究了一维无限格点自旋1的键交替反铁磁XXZ海森伯模型中的量子相变.分别计算了系统的von Neumann熵、单位格点保真度和序参量,从而得到了系统随键交替强度的变化从拓扑有序Néel相到局域有序二聚化相的量子相变点.我们用矩阵乘积态方法拟合出了相变的中心荷c?0.5,表明此相变属于二维经典的Ising普适类.另外,通过对拓扑Néel序的数值拟合,我们得到了相变点处的特征临界指数β′=0.236和γ′=0.838.     

Quantum Phase Transitions and Dimerized Phases in Frustrated Spin Ladder

In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group (DMRG) algorithm. Effect of the intra-chain next-nearest-neighbor (NNN) super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases.     

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.     

具有Dzyaloshinskii-Moriya相互作用的XY模型的量子相干性

研究了具有Dzyaloshinskii-Moriya(DM)相互作用的一维横场XY自旋链的量子相变和量子相干性.采用约旦-维格纳变换严格求解了哈密顿量,并描绘了体系的关联函数和相图,相图包含反铁磁相、顺磁相和螺旋相.利用相对熵和Jensen-Shannon熵讨论了XY模型的量子相干性.研究发现,相对熵与Jensen-Shannon熵所表现的行为都可以很好地表征该模型的量子相变.非螺旋相中量子相干性不依赖DM相互作用,而在螺旋相DM相互作用对量子相干性有显著影响.此外,指出了在带有DM相互作用的这一类反射对称破缺体系中关联函数计算的常见问题.     

关于Lewis-Riesenfeld相位和量子几何相位

评注了《大学物理》21 23一文关于量子几何相位与Lewis相位论述与《物理学报》48 2018一文的结论有极大不同.指出前者对Lewis导出的相位与量子几何相位关系的错误陈述，而后者的结论是正确的. 关键词： 量子几何相位 不变量方法 Lewis-Riesenfeld相位     

Quantum Phase Dynamics of Interaction between Photon Field and Magnetic System: Effects of Magnetic Quantum Tunnelling

We investigate the dynamics of probability distributions of an initially one-mode coherent field interacting with a four-state molecular system, which is a single magnet with a tunneling across an anisotropic barrier, using a numerically exact approach. The population for each state, the phase properties of and , and ), the entropy are calculated for a model system. The model predicts that the molecule and field become asymptotically disentangled at half of the revival time, and that optical Schrödinger-cat and magnetic Schrödinger-cat states are generated.This paper was originally presented at the 5th International Conference on NEAR FIELD OPTICS and RELATED TECHNOLOGIES (NFO-5), which was held on December 6–10, 1998 at Coganoi Bay Hotel, Shirahama, Japan, in cooperation with the Japan Society of Applied Physics and Mombusho Grant-in Aid for Scientific Research on Priority Areas “Near-field Nano-optics” Project, sponsored by Japan Society for the Promotion of Science.     

Quantum phase for an electric quadrupole moment in noncommutative quantum mechanics

We study the noncoInmutative nonrelativistic quantum dynamics of a neutral particle, which possesses an electric qaudrupole moment, in the presence of an external magnetic field. First, by intro ducing a shift for the magnetic field, we give the Schrodinger equations in the presence of an external magnetic field both on a noncommutative space and a noncomlnutative phase space, respectively. Then by solving the SchrSdinger equations both on a noneommutative space and a noncommutative phase space, we obtain quantum phases of the electric quadrupole moment, respectively. Wc demonstrate that these phases are geometric and dispersive.