Linear entropy dynamics of the field in the Jaynes－Cummings model with an intensity-dependent coupling in the dispersive approximation

We present the linear entropy dynamics of the field state in the dispersive cavity in the Jaynes－Cummings model with an intensity-dependent coupling in the dispersive approximation, and investigate the influence of dissipation on entanglement between the field and the atoms. We show that the coherence properties of the field are also affected by the cavity when the nonlinear process of the field interacting with the atoms with an intensity-dependent coupling is involved, and find that the dissipation constant, the intensity of the field and the atomic distribution angle have different influence on the coherence properties of the field.     

结构缺陷对量子波导腔中热导的调控

利用散射矩阵方法和标量模型,研究了低温下可调缺陷对量子波导腔的热导的影响. 改变缺陷的参数能控制热导,缺陷的尺寸和位置能导致热导的改变,而且不同种类的缺陷也能导致热导随温度的变化. 关键词： 声学声子输运 热导 量子结构     

Entropy squeezing for a two-level atom in the Jaynes－Cummings model with an intensity-depend coupling

We study the squeezing for a two-level atom in the Jaynes－Cummings model with intensity-dependent coupling using quantum information entropy, and examine the influences of the initial state of the system on the squeezed component number and direction of the information entropy squeezing. Our results show that, the squeezed component number depends on the atomic initial distribution angle, while the squeezed direction is determined by both the phases of the atom and the field for the information entropy squeezing. Quantum information entropy is shown to be a remarkable precision measure for atomic squeezing.     

Simulating Entangling Unitary Operator Using Non-maximally Entangled States

We use non-maximally entangled states （NMESs） to simulate an entangling unitary operator （EUO） with a certain probability. Given entanglement resources, the probability of the success we achieve is a decreasing function of the parameters of the EUO. Given an EUO, for certain entanglement resources the result is optimal, i.e., the probability obtains a maximal vaiue, and for optimal result higher parameters of the EUO match more amount of entanglement resources. The probability of the success we achieve is higher than the known results under some condition.     

Thermal conductance in a two-slit quantum waveguide

Using the scattering-matrix method, we investigate the thermal conductance in a two-slit quantum waveguide at low temperature. The results show that the total thermal conductance decreases monotonically with temperature increasing. Moreover, we find that the behaviours of the thermal conductance versus temperature are different for different types of slits.     

界面铁掺杂锯齿形石墨烯纳米带的自旋输运性能

基于密度泛函理论第一原理系统研究了界面铁掺杂锯齿(zigzag)形石墨烯纳米带的自旋输运性能, 首先考虑了宽度为4的锯齿(zigzag)形石墨烯纳米带, 构件了4个纳米器件模型, 对应于中心散射区的长度分别为N=4, 6, 8和10个石墨烯单胞的长度, 铁掺杂在中心区和电极的界面. 发现在铁磁(FM)态, 四个器件的β自旋的电流远大于α自旋的电流, 产生了自旋过滤现象; 而界面铁掺杂的反铁磁态模型, 两种电流自旋都很小, 无法产生自旋过滤现象; 进一步考虑电极的反自旋构型, 器件电流显示出明显的自旋过滤效应. 探讨了带宽分别为5和6的纳米器件的自旋输运性能, 中心散射区的长度为N=6个石墨烯单胞的长度, FM 态下器件两种自旋方向的电流值也存在较大的差异, β自旋的电流远大于α自旋电流. 这些结果表明: 界面铁掺杂能有效调控锯齿形石墨烯纳米带的自旋电子, 对于设计和发展高极化自旋过滤器件有重要意义.     

功能化扶手椅型石墨烯纳米带异质结的磁器件特性

石墨烯在未来纳米电子器件领域具有广泛的应用前景, 但是基于扶手椅型石墨烯纳米带(AGNR)的磁输运性质的研究还比较少. 本文理论上提出AGNR边缘桥接过渡金属Mn原子, 再用双F 原子(或双H原子)饱和形成特殊化学修饰的纳米带(AGNR-Mn-F₂或AGNR-Mn-H₂), 并运用基于第一性原理和非平衡态格林函数相结合的方法对其磁输运性质进行理论计算. 结果表明: 这两种纳米带所构成的异质结(F₂-AGNR-Mn-H₂)具有优良的磁器件特性, 即在很宽的偏压范围内, 能实现100%的自旋极化, 且在P(在左右电极垂直加上相同方向的磁场)和AP构型(在左右电极垂直加上相反方向的磁场)时, 分别具有单自旋和双自旋过滤效应; 同时发现, 这种异质结也具有双自旋二极管效应, 它的最大整流比可达到10⁸. 此外, 改变开关磁场的方向, 即从一种磁构型变换为另一种磁构型时, 能产生明显的自旋阀效应, 其巨磁阻高达10⁸%. 这意味着这种特殊的异质结能同时实现优良的自旋过滤、双自旋二极管及巨磁阻效应, 这对于发展自旋磁器件有重要意义.     

双一流背景下研究生高等量子力学优质课程建设和改革探讨——以长沙理工大学为例

高等量子力学是物理学在读硕士研究生必修的专业基础课程之一.该课程具有较抽象、难理解、深奥等特点，学生学习起来相对困难，教学效果不佳，而优质的课程将会大大提高学生的学习效果.以长沙理工大学为例，从教学内容、教学方法、课程优势及特色、课程存在的问题及解决方法等各方面，详细介绍了建设高等量子力学优质课程的一些具体措施和方法.