微管壁上量子信息的传递

微管管壁上的原丝纤维可以描述成各项异性的二维赝自旋模型,其最小重复单元是三角形状的。在这个模型中存在三种不同的“自旋-自旋”相互作用。而每一维上的自由电子可以看作是赝自旋模型。那么,微管壁上的量子信息传递就可以用Lylod提出的激光控制量子计算的模型来解释。Microtubule （MT） is described as an anisotropic two-dimensional pseudo-spin model on a triangular lattice, in which there are three different ＂spin-spin＂ interactions. The mobile electron in each lattice site is described based on the pseudo-spin model. Then, the processing of quantum information in the MT wall is presented by virtue of the scheme of driving quantum computer in sequence of laser pulse developed by Lloyd.     

黑洞量子理论

简述引力场中物质的量子效应——黑洞的Ｈａｗｋｉｎｇ辐射，并进一步讨论黑洞的量子理论，给出一些结论。     

过渡金属络合分子二步自旋转换量子理论

本文建立了d4,6络合分子二步自旋转换的量子理论.模拟计算得出了如下几点结论:①低对称畸变是d4,6络合分子可以发生二步自旋转换的必要条件;②对于具有任何一种低对称性的任何一种d4,6络合物存在这种低对称畸变的一个临界值,当畸变小于临界值时只可发生一步自旋转换,即HS LS自旋转换;而当畸变大于临界值时则可以发生二步自旋转换,即HS MS和MS LS自旋转换.二步自旋转换导致磁矩曲线上产生两个拐点,与两个自旋转换点相对应,其间的Dq-距离ΔDq随畸变量的增加而增加;③当畸变量等于临界值时络合分子的两个自旋转换点相重迭,即与自旋转换有关的HS、MS、LS三个能级交于一点,这形成一个自旋三相点,它代表一个由三种自旋相形成的临界状态.因此,自旋三相态或许是可以实现的;④低对称畸变将使高自旋磁矩明显增大,可以高于6.10μB.这表明,通常用实验磁矩数据来判断络合物中心为何种离子的方法是不可靠的;⑤低自旋磁矩可以小于1但显大于0,表明在络合分子中过渡金属离子的轨道角动量未完全碎灭的情况.     

爱因斯坦与量子理论

 如果说普朗克创立量子学说贡献巨大的话,那么,爱因斯坦在此领域作出的贡献同样杰出。从一定意义上说,没有爱因斯坦的努力,也就没有近代量子理论的形成。 爱因斯坦１９０５年发表的《关于光的发射和转化的一个启发性观点》一文,明确阐述了他的光量子（能量元）思想,指出：用连续的空间函数表示的光的波动理论正确地说明了纯光学现象而且可能永远不会被其他理论代替;但要记住,光学观测总是指时间平均值而非瞬时值。尽管该理论在衍射、反射、折射、散射等方面已完全为实验证实,但仍可以想象,将它应用到光的发射或转换等现象时会与实验发生矛盾。     

三维量子自旋玻璃理论(Ⅲ)──replica对称破缺解

利用推广的Ｐａｒｉｓｉ量子ｒｅｐｌｉｃａ对称破缺方案，将我们以前提出的理论推广到ｒｅｐｌｉｃａ对称破缺，获得一组新的自旋自作用和自旋玻璃序参数的自洽方程，导出局域磁化率．通过计算ｒｅｐｌｉｃａ对称破缺自由能，发现矢量自旋玻璃模型的ｍｐｌｉｃａ对称解存在着低温破缺． 关键词：     

弯曲应变下六角晶格量子反铁磁体的赝朗道能级

利用线性自旋波理论和量子蒙特卡罗方法研究了弯曲应变下六角晶格量子反铁磁体的赝朗道能级.通过线性自旋波理论,发现磁赝朗道能级出现在磁子能谱的高能端,其能级间距与能级指数的平方根成正比.线性自旋波理论和量子蒙特卡罗方法都显示,尺寸相同时随着应变强度的逐渐增加,局域磁化强度逐渐减弱,应变强度相同的条件下反铁磁序在y方向上连续减弱,因为上边界处的海森伯链解耦为孤立的垂直链,导致上边界附近的磁序被破坏.量子蒙特卡罗方法提供了更精确的反铁磁序演化:在特定应变强度下上边界处垂直关联不变,水平关联增加,从而影响磁化强度,使局域磁化在上边界处呈上翘趋势.研究结果有助于理解弯曲应变对自旋激发的影响,并可能在二维量子磁性材料实验中得以实现.     

量子理论的伟大奠基者——普朗克

  德国物理学家马克斯•普朗克(Max Karl Ernst Ludwig Planck, 1858~1947) 在解决经典物理学的困难——黑体辐射问题时,提出能量子假说,引入了一个常数h,并因此荣膺1918年的诺贝尔物理学奖。     

石墨烯中新奇量子物态的研究

石墨烯特殊的晶格结构和能带结构赋予了它独特的电学性质.近年来,分数量子霍尔态、魔角石墨烯中的关联绝缘体态和超导态等现象的发现不断证明着石墨烯是一种理想的二维模型体系,可用于实现一系列新奇的量子物态,对石墨烯中新奇量子物态的探测和调控也一直是凝聚态物理领域的前沿研究热点之一.本文将系统地介绍近年来石墨烯中对称性破缺量子物态的研究进展,包括平带中强关联量子物态的研究以及谷赝自旋调控的研究,并介绍一种在纳米尺度、单电子精度上探测二维材料体系简并度及对称性破缺态的普适方法,希望为相关领域的研究人员提供参考和借鉴.     

三维量子自旋玻璃理论(Ⅱ)——稳定性分析

利用我们提出的三维量子自旋玻璃理论,通过引入一个量子的Goldbart去耦方案,将三维量子自旋玻璃的稳定性Hessian矩阵的本征值问题转化为类伊辛自旋玻璃的相应问题,并求出了所有的本征值。通过分析最小本征值,获得了Almeida-Thouless(AT)下临界线和Gabay-Toulouse(GT)上临界线所满足的方程。最后,数值研究了不同自旋的AT不稳定性并讨论了我们的理论与热场动力学方法、集团展开方法的联系。     

三量子比特系统中单个谐振子诱导的量子关联

我们考虑初始无关联并且与由一个谐振子构成的环境之间互相耦合的三量子比特系统。通过研究量子比特-环境的耦合强度以及量子比特初始态对量子关联的影响,我们发现环境可以诱导量子关联,提出并证明了四个命题阐述谐振子如何调控三个量子比特中量子关联的分布。给出了产生量子关联的条件。特别地,对于弱耦合,我们不但能够获得很多的量子关联,而且还使量子比特系统和环境始终处于分离态。一般地,量子关联动力学是很复杂 的,这是由于环境起着两个互相竞争的作用：一方面诱导出各个比特之间的量子关联;另一方面又使它们发生消相干,从而破坏量子关联。     

细胞骨架微管中水分子Kerr效应对电磁场辐射的影响

微管是细胞骨架的主要组成成分和功能组件,其中充满了属于Kerr介质的液体水。本文运用量子场论路径积分方法,研究微管中水分子与电磁场的相互作用。为了考虑Kerr效应,在系统的哈密顿量中引入电磁场的非谐项。我们给出了含有Kerr非线性项的电磁辐射运动方程,进而讨论了Kerr效应对电偶极子集体辐射的影响。     

Free-Fall Non-Universality in Quantum Theory

The author shows by embodying the Einstein equivalence principle—local Poincaré invariance—and general covariance in quantum theory that wave-function spreading rules out the universality of free fall, that is, the free-fall trajectory of a quantum (test) particle depends on its internal properties. The author provides a quantitative estimate of the free-fall non-universality in terms of the Eötvös parameter, which turns out to be measurable in atom interferometry.     

Quantum Set Theory

The complete orthomodular lattice of closed subspaces of a Hilbert space is considered as the logic describing a quantum physical system, and called a quantum logic. G. Takeuti developed a quantum set theory based on the quantum logic. He showed that the real numbers defined in the quantum set theory represent observables in quantum physics. We formulate the quantum set theory by introducing a strong implication corresponding to the lattice order, and represent the basic concepts of quantum physics such as propositions, symmetries, and states in the quantum set theory.     

Conventions in Relativity Theory and Quantum Mechanics

The conventionalistic aspects of physical world perception are reviewed with an emphasis on the constancy of the speed of light in relativity theory and the irreversibility of measurements in quantum mechanics. An appendix contains a complete proof of Alexandrov's theorem using mainly methods of affine geometry.     

Anthropic Interpretation of Quantum Theory

The problem of interpreting quantum theory on a large (e.g. cosmological) scale has been commonly conceived as a search for objective reality in a framework that is fundamentally probabilistic. The Everett programme attempts to evade the issue by the reintroduction of determinism at the global level of a state vector of the universe. The present approach is based on the recognition that, like determinism, objective reality is an unrealistic objective. It is shown how an objective theory of an essentially subjective reality can be set up using an appropriately weighted probability measure on the relevant set of Hilbert subspaces. It is suggested that an entropy principle (superseding the weak anthropic principle) should be used to provide the weighting that is needed. The application of this ansatz to a toy gedanken example (involving Schroedinger's legendary cat) is described in an appendix.     

Effective Field Theory of Random Quantum Circuits

Quantum circuits have been widely used as a platform to simulate generic quantum many-body systems. In particular, random quantum circuits provide a means to probe universal features of many-body quantum chaos and ergodicity. Some such features have already been experimentally demonstrated in noisy intermediate-scale quantum (NISQ) devices. On the theory side, properties of random quantum circuits have been studied on a case-by-case basis and for certain specific systems, and a hallmark of quantum chaos—universal Wigner–Dyson level statistics—has been derived. This work develops an effective field theory for a large class of random quantum circuits. The theory has the form of a replica sigma model and is similar to the low-energy approach to diffusion in disordered systems. The method is used to explicitly derive the universal random matrix behavior of a large family of random circuits. In particular, we rederive the Wigner–Dyson spectral statistics of the brickwork circuit model by Chan, De Luca, and Chalker [Phys. Rev. X 8, 041019 (2018)] and show within the same calculation that its various permutations and higher-dimensional generalizations preserve the universal level statistics. Finally, we use the replica sigma model framework to rederive the Weingarten calculus, which is a method of evaluating integrals of polynomials of matrix elements with respect to the Haar measure over compact groups and has many applications in the study of quantum circuits. The effective field theory derived here provides both a method to quantitatively characterize the quantum dynamics of random Floquet systems (e.g., calculating operator and entanglement spreading) and a path to understanding the general fundamental mechanism behind quantum chaos and thermalization in these systems.