共查询到20条相似文献，搜索用时 31 毫秒
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对于Hamiltonian随时间作周期变化的量子系统中状态的演化,Bloch定理亦成立,并可据此定义一种新的几何相位———Bloch相位．证明用这种新的几何相位可以把迄今发现的所有同步（即量子态演化一周后获得的）几何相位统一起来,即Bloch相位等于Pancharatnam相位、Aharonov-Anandan相位和Lewis-Riesenfeld相位,并且在绝热条件下化为Bery相位．为此,先对Pancharatnam相位、Aharonov-Anandan相位和Lewis-Riesenfeld相位的定义作等价的改变,使它们变得有物理意义,并把Lewis-Riesenfeld相位和Berry相位推广到简并情形．还讨论了Bloch相位的求解问题关键词： 相似文献
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在绝热演化中的几何相位（即Berry相位）被推广到包括非本征态的一般量子态.这个新的几何相位同时适用于线性量子系统和非线性量子系统.它对于后者尤其重要因为非线性量子系统的绝热演化不能通过本征态的线性叠加来描述.在线性量子系统中,新定义的几何相位是各个本征态Berry相位的权重平均. 相似文献
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量子体系演化的几何相位 总被引：4，自引：0，他引：4
量子体系在演化过程中,其状态的时间演化因子除众所周知的由系统能谱决定的动力学相位因子外,还会出现与系统演化路径有关的几何相位因子即Berry相位因子。几何相位的存在已为大量实验所证实,在理论上,已确定了其数学基础是纤维丛理论,并发现它与规范场有某些联系。本文评述了有关几何相位研究工作的进展。 相似文献
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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 总被引：5，自引：5，他引：0
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。 相似文献
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文章研究了自旋为1的粒子在旋转磁场中的几何相位和动力学相位.推导出如何计算自旋为1的粒子在绝热和非绝热演化中的几何相位和动力学相位公式,并利用这些公式计算其相位.最后我们讨论了三种情况下的Berry相位,当考虑ω1<<ω时,系统处于绝热近似,此时,几何相位就是Berry相位. 相似文献
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对曾谨言所著的量子力学书中量子几何相位的一些错误概念再次提出了批评,同时针对他在《大学物理》上的《介绍几个量子力学基本概念》一文的有关观点进行了逐点分析批驳,并举出Berry论文中有关论述为证．本文着重从“正确”和“真实”两方面去分析． 相似文献
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文章首先概述了近年国际文献中关于量子绝热近似和绝热条件的不自洽性的研究.叙述了文献中关于绝热近似不自洽性的论证和争论.然后引入文章作者的观点,从不同于国外文献的角度出发指出应当正确地理解瞬时本征函数的相位问题,从这个相位的正确处理,得出结论:(1)MS不自洽的存在,不因计及几何相位而消除;(2)量子几何相位不自洽是不存在;(3)现时的标准的绝热近似条件不是充分条件. 相似文献
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文章首先概述了近年国际文献中关于量子绝热近似和绝热条件的不自洽性的研究.叙述了文献中关于绝热近似不自洽性的论证和争论.然后引入文章作者的观点,从不同于国外文献的角度出发指出应当正确地理解瞬时本征函数的相位问题,从这个相位的正确处理,得出结论：（1）MS不自洽的存在,不因计及几何相位而消除;（2）量子几何相位不自洽是不存在;（3）现时的标准的绝热近似条件不是充分条件. 相似文献
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文章首先概述了近年国际文献中关于量子绝热近似和绝热条件的不自洽性的研究．叙述了文献中关于绝热近似不自洽性的论证和争论．然后引入文章作者的观点，从不同于国外文献的角度出发指出应当正确地理解瞬时本征函数的相位问题，从这个相位的正确处理，得出结论：（1）MS不自洽的存在，不因计及几何相位而消除；（2）量子几何相位不自洽是不存在；（3）现时的标准的绝热近似条件不是充分条件． 相似文献
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正负材料交界面上光波的额外相位跃变 总被引：1，自引：0，他引：1
研究了正负材料交界面上光波因螺旋度瞬时翻转所导致的额外相位。在构造有效哈密顿量的基础之上,我们运用Lewis—Riesenfeld不变量理论及与不变量有关的么正变换方法分析和计算了这一相位。由于交界面上螺旋度倒转是一个含时过程,我们计算了其中由光子波函数获得的几何相位。光子螺旋度倒转类似数字电路0与1之间的互换操作,文中简要讨论了它可能具有的信息论意义。 相似文献
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由于绝热条件几何相位量子逻辑门存在非绝热差错与退相干差错这一冲突,因此在拓扑量子计算中需要设计非绝热条件几何相门,以克服这一不足.证明螺旋光纤系统内光子有效哈密顿量恰好是一个Wang Matsumoto型哈密顿量,因此螺旋光纤系统能自动产生非绝热条件几何相移.同时还证明在螺旋光纤方案中,由极化光子与螺旋光纤相互作用哈密顿量所导致的动力学相位为零（这正是拓扑量子计算所要求的）,以及在螺旋光纤系统中可以通过控制极化光子初始波矢,从而较容易获得条件初始态.总之,螺旋光纤系统方案能自动满足Wang与Matsumoto的核磁共振方案中为实现非绝热条件几何相移所提出的全部条件与要求.关键词：几何相位螺旋光纤系统Wang Matsumoto型哈密顿量拓扑量子计算 相似文献
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We introduce a quantum geometric tensor in a curved space with a parameter-dependent metric, which contains the quantum metric tensor as the symmetric part and the Berry curvature corresponding to the antisymmetric part. This parameter-dependent metric modifies the usual inner product, which induces modifications in the quantum metric tensor and Berry curvature by adding terms proportional to the derivatives with respect to the parameters of the determinant of the metric. The quantum metric tensor is obtained in two ways: By using the definition of the infinitesimal distance between two states in the parameter-dependent curved space and via the fidelity susceptibility approach. The usual Berry connection acquires an additional term with which the curved inner product converts the Berry connection into an object that transforms as a connection and density of weight one. Finally, we provide three examples in one dimension with a nontrivial metric: an anharmonic oscillator, a Morse-like potential, and a generalized anharmonic oscillator; and one in two dimensions: the coupled anharmonic oscillator in a curved space. 相似文献
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Bingyi Liu Basudeb Sain Bernhard Reineke Ruizhe Zhao Cedrik Meier Lingling Huang Yongyuan Jiang Thomas Zentgraf 《Advanced Optical Materials》2020,8(9)
Nonlinear Pancharatnam–Berry phase metasurfaces facilitate the nontrivial phase modulation for frequency conversion processes by leveraging photon‐spin dependent nonlinear geometric‐phases. However, plasmonic metasurfaces show some severe limitation for nonlinear frequency conversion due to the intrinsic high ohmic loss and low damage threshold of plasmonic nanostructures. Here, the nonlinear geometric‐phases associated with the third‐harmonic generation process occurring in all‐dielectric metasurfaces is studied systematically, which are composed of silicon nanofins with different in‐plane rotational symmetries. It is found that the wave coupling among different field components of the resonant fundamental field gives rise to the appearance of different nonlinear geometric‐phases of the generated third‐harmonic signals. The experimental observations of the nonlinear beam steering and nonlinear holography realized in this work by all‐dielectric geometric‐phase metasurfaces are well explained with the developed theory. This work offers a new physical picture to understand the nonlinear optical process occurring at nanoscale dielectric resonators and will help in the design of nonlinear metasurfaces with tailored phase properties. 相似文献
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Geometric phases are robust to local noises and the nonadiabatic ones can reduce the evolution time, thus nonadiabatic geometric gates have strong robustness and can approach high fidelity. However, the advantage of geometric phase has not been fully explored in previous investigations. Here,a scheme is proposed for universal quantum gates with pure nonadiabatic and noncyclic geometric phases from smooth evolution paths. In the scheme, only geometric phase can be accumulated in a fast way, and thus it not only fully utilizes the local noise resistant property of geometric phase but also reduces the difficulty in experimental realization. Numerical results show that the implemented geometric gates have stronger robustness than dynamical gates and the geometric scheme with cyclic path. Furthermore, it proposes to construct universal quantum gate on superconducting circuits, with the fidelities of single-qubit gate and nontrivial two-qubit gate can achieve 99.97% and 99.87%, respectively. Therefore, these high-fidelity quantum gates are promising for large-scale fault-tolerant quantum computation. 相似文献
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We study exact single-soliton solutions of an attractive Bose-Einstein condensate governed by a one-dimensional nonautonomous Gross-Pitaevskii system. For several different forms of time-dependent atom-atom interaction and external parabolic potential which satisfy the exact integrability scenario, we construct a set of new analytical nonautonomous deformed-soliton solutions, including the macroscopic wave function and the position of soliton＇s center of mass. The soliton characteristics are modulated by the external field parameters and deformation factors related to the number of the condensed atoms and the initial conditions. The results suggest a simple and effective method for experimentally generating matter-wave deformed solitons and manipulating their motions. 相似文献
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