量子谐振子与经典谐振子的比较

运用广义线性量子变换的普遍理论求解了量子谐振子,同经典谐振子比较给出了量子谐振子趋近于经典极限的条件,并得出相干态是最理想的经典极限态．     

无限深方势阱本征值和本征态的三种求解方法

一维无限深方势阱模型是量子力学理想模型,经典教材中势阱的边界一般取得比较特殊.或关于坐标原点具有对称性,或势阱左边界位于坐标原点.本文首先展示了如何利用3种方法求解一维任意边界无限深方势阱能量本征值和对应的本征态,不同方法得到的结果彼此之间等价,讨论分析了这3种方法的推导结果,然后得到关于一维任意边界无限深方势阱能量本征值和本征态的通式,从中比较容易看出这两个物理量均与阱宽有关,并且本征波函数与边界值有关,最后将一维结果拓展到二维和三维任意边界无限深方势阱情况.     

球坐标中三维各向同性谐振子的类经典态

把坐标平均值随时间的变化和在宏观条件下与经典解相同的量子态定义为类经典态(NCS), 并求解球坐标中三维各向同性谐振子的NCS问题, 有助于从波动力学角度理解量子到经典过渡的问题. 选与经典态相应的大量子数附近的矩形波包作为NCS, 得到与经典解一致的结果, 但NCS不是惟一的. 一个经典态可以有很多NCS与之对应, 就像一个热力学态可以有无数力学态与之对应一样, 从量子到经典的描述是一个粗粒化和信息丢失的过程.     

无限深势阱中粒子的态密度

对于自由粒子在有限容器中的能态密度,热力学统计教材一般根据半经典量子图像,由驻波条件和德布罗意关系,以动量分立值为基础出发得到;然而根据量子理论,无限深势阱中的粒子存在能量本征态,而非动量本征态.本文以能量本征态为统计对象推导了有限体积中的自由粒子的能态密度,结果与教材一致.但是我们的处理方式显得更为自然.     

量子力学的整体性概念和概率诠释的物理内涵

本文回答了文献1～2对量子力学提出的疑问.基于量子力学的整体性概念指出,Landau和Lifshitz给出的一维无限深方势阱中粒子的动能概率分布函数是正确的,Pauli等人给出的概率分布函数是不正确的.从量子测量理论的角度讨论了一维谐振子的动量概率分布问题,并且指出势能大于本征能量的概率不为零并不表示存在负动能的概率分布区域。     

二维无限深方势阱中粒子运动的路径积分解法

用路径积分的方法计算了二维无限深方势阱中粒子的传播子,并由传播函数推导出二维无限深方势阱中粒子的波函数和能量,进一步体现了路径积分与其他经典量子化方法的等价性,反映了路径积分应用于难以处理的量子力学问题的价值.     

q变形非简谐振子广义相干态的叠加态及其非经典特性

给出了q变形非简谐振子广义相干态的叠加态,研究了这种叠加态的量子统计特性,并就叠加相位δ和形变参数q对这些特性的影响进行了讨论.结果表明,当δ分别趋近于0和π2时,叠加相干态的非经典特性分别趋近于q变形非简谐振子奇偶广义相干态的结果,并且q偏离1越大,这种非经典特性越明显.     

Wigner函数的性质及其在一维无限深势阱和一维谐振子中的应用

首先介绍了Wigner函数的基本性质以及以Wigner函数为基础的相空间定态微扰理论,然后将其应用到一维无限深势阱和谐振子。 推导出一维无限深势阱所对应的Wigner函数,而且发现了存在于其纯态Wigner函数中奇特的压缩效应, 并利用不确定性关系给予了解释。同时计算出一维无限深势阱和谐振子在微扰的作用下,相应Wigner函数和能级的修正。 In this article, the qualities of Wigner function and the corresponding stationary perturbation theory are introduced and applied to one dimensional infinite potential well and one dimensional harmonic oscillator, and then the particular Wigner function of one dimensional infinite potential well is specified and a special constriction effect in its pure state Wigner function is discovered, to which, simultaneously, a detailed and reasonable explanation is elaborated from the perspective of uncertainty principle. Ultimately, the amendment of Wigner function and energy of one dimensional infinite potential well and one dimensional harmonic oscillator under perturbation are calculated according to stationary phase space perturbation theory.     

(nc-Si/SiO2)/SiO2多层量子点结构的激子能级

采用球型量子点模型,应用有效质量近似理论,研究了(nc-Si/SiO2)/SiO2多层量子点结构的激子能级和波函数.结果表明,有限深势阱模型的引入更符合实际更加准确.无论在无限深或有限深势阱下,激子质心运动部分基态能量随最子点半径的减小而急剧增大.对于相同的量子点半径α,无限深势阱下的质心部分能量总比有限深势阱高,且二者的差距随α的减小小而增大.     

基于MATLAB的能级、波函数及几率密度图形的绘制

本文着重介绍运用Mafia5编程语言完成一维无限深势阱和线性谐振子的能级、渡函数及几率密度图形的绘制问题。     

Effects of entanglement on the scattering intensity of neutron compton scattering by a proton pair in solids

We calculate scattering functions S(q-->,omega) of neutron Compton scattering (NCS) for a proton (deuteron) pair in the entangled state caused by the indistinguishability of particles. From the calculation, it is concluded that the effect of entanglement on the scattering intensity is undetectable in NCS experiments because of their high energy transfer and broad energy resolution.     

Crystal structure and spin state of Fe0.5Co0.5(NCS)2(bpa)2

Fe(NCS)₂(bpa)₂, Co(NCS)₂(bpa)₂, and Fe_0.5Co_0.5(NCS)₂(bpa)₂ were synthesized. X-ray structural analysis revealed that the structure was the same among the three complexes. Although the metal-ligand distance in the mixed crystals was shorter than the distance in Fe(NCS)₂(bpa)₂ and was similar to that in Co(NCS)₂(bpa)₂, the spin state remained temperature-independent Fe^II high-spin state in ⁵⁷Fe M?ssbauer spectra.     

On nonlinear coherent states properties for electron-phonon dynamics

This work addresses a construction of a dual pair of nonlinear coherent states (NCS) in the context of changes of bases in the underlying Hilbert space for a model pertaining to an electron-phonon model in the condensed matter physics, obeying a f-deformed Heisenberg algebra. The existence and properties of reproducing kernel in the NCS Hilbert space are studied and discussed; the probability density and its dynamics in the basis of constructed coherent states are provided. A Glauber-Sudarshan P-representation of the density matrix and relevant issues related to the reproducing kernel properties are presented. Moreover, a NCS quantization of classical phase space observables is performed and illustrated in a concrete example of q-deformed coherent states. Finally, an exposition of quantum optical properties is given.     

非中心对称超导序参量研究

非中心对称超导体是近年发现的一类新型超导材料. 在这类材料中, 非中心对称的晶体势场产生一个有效的反对称自旋-轨道耦合(ASOC)并导致自旋简并的能级发生分裂, 从而在超导配对态中允许自旋单态和自旋三重态混合. 这一性质有别于先前研究的大部分超导体, 需要从概念上突破BCS理论框架. 此外, 理论研究还表明非中心对称超导可能还是一类潜在的拓扑超导材料. 这些独特的物理性质已激发了广泛的研究兴趣, 并且越来越受到关注.#br#超导序参量的对称性是认识和理解超导形成机理的一个重要物理量. 本文将介绍基于隧道二极管的伦敦穿透深度测量技术, 并简要综述非中心对称超导的研究现状以及穿透深度测量在非中心对称超导序参量研究中的应用. 通过对比研究具有不同反对称自旋-轨道耦合强度的非中心对称超导材料, 我们发现其混合超导配对态与反对称自旋-轨道耦合强度缺乏简单的对应关系, 但与能带劈裂(E_ASOC)相对于超导转变温度(T_c)的比值(E_r=E_ASOC/T_c)紧密相关.     

Spin Josephson current in a ferromagnet/noncentrosymmetric superconductor junction

We investigate the equilibrium spin transport in a ferromagnet/noncentrosymmetric superconductor (FM/NCS) junction where the NCS has a dominant triplet order parameter and helical edge state. Based on the symmetry analysis and numerical calculation, we demonstrate that there is a nonzero spin supercurrent flowing in the junction, which stems from the exchange coupling between the FM magnetization and triplet Cooper-pair spin. It is also found that a transverse spin current other than the helical edge spin current is flowing along the interface of the junction, and its polarization is related to the longitudinal spin supercurrent. Besides, an equilibrium Hall current is also shown to flow along the junction’s interface due to the broken time-reversal symmetry from the FM.     

Rabi-type oscillations in a classical Josephson junction

We study analytically and numerically the phase-modulation properties of a classical Josephson tunnel junction biased in the zero-voltage state and phase locked to an external ac field. We show that the phase-locked state is being modulated in the transients, or in response to perturbations, and the modulation frequency is calculated as a function of relevant system parameters, such as microwave field amplitude. Our analysis demonstrates that the modulation of a phase-locked state in an entirely classical Josephson junction produces oscillations analogous to quantum mechanical Rabi oscillations, expected to be observed under the same conditions.     

Quantum simulation of classical thermal states

We establish a connection between ground states of local quantum Hamiltonians and thermal states of classical spin systems. For any discrete classical statistical mechanical model in any spatial dimension, we find an associated quantum state such that the reduced density operator behaves as the thermal state of the classical system. We show that all these quantum states are unique ground states of a universal 5-body local quantum Hamiltonian acting on a (polynomially enlarged) qubit system on a 2D lattice. The only free parameters of the quantum Hamiltonian are coupling strengths of two-body interactions, which allow one to choose the type and dimension of the classical model as well as the interaction strength and temperature. This opens the possibility to study and simulate classical spin models in arbitrary dimension using a 2D quantum system.     

Quantum and classical correlations for a two-qubit X structure density matrix

We derive explicit expressions for quantum discord and classical correlation for an X structure density matrix. Based on the characteristics of the expressions, the quantum discord and the classical correlation are easily obtained and compared under different initial conditions using a novel analytical method. We explain the relationships among quantum discord, classical correlation, and entanglement, and further find that the quantum discord is not always larger than the entanglement measured by concurrence in a general two-qubit X state. The new method, which is different from previous approaches, has certain guiding significance for analysing quantum discord and classical correlation of a two-qubit X state, such as a mixed state.     

Effect of tensile strain on optical properties of AlGaP-based neighboring confinement structure

We report on the effect of tensile strain on optical properties of AlGaP-based neighboring confinement structure (NCS). Enhancement of photoluminescence (PL) intensity was observed from tensilely strained NCS, compared with unstrained NCS. In addition, drastic improvement of the activation energy for thermal quenching was achieved by introduction of tensile strain to NCS in spite of the reduction of the band discontinuity. These improvements were attributed to the modification of the band structure and the local-strain variation due to the alloy randomness of the InGaP buffer layer.