Rashba自旋轨道耦合下宽量子线中的自旋流

利用硬壁限制势下Rashba自旋轨道耦合量子线波函数以及一个自旋流定义来计算宽量子线中的自旋流密度,得到了两个非零线自旋流密度分量及一个净自旋流密度,发现随着量子线通道数及Rashba自旋轨道耦合作用的增加以上三个自旋流密度会随之增强,此外利用自旋流产生的可被检测电场可提供一个对自旋流进行检测和调控的方法.     

量子线中通过双杂质的共振传输

1　Introduction　Quantumtransportinmesoscopicsystemshasbeenextensivelyinvestigatedinthe pasttwodecades[1] .SinceWeesetal[2 ] .andWharametal[3] .discoveredthe phenomenonofconductance quantizationofanelectronthroughanarrow pointcontactstructure ,therehavebeenanumberofotherworkswhichcon centratedonstudyingelectronscatteringfromimpuri tiesinanarrowquantumconductorwire .BagwellandAvishaietal[4 9] .haveexaminedtheinfluencesofscatteringfromimpuritiesontheelectrontransmis sioninquantumwirebyusingthe…     

局域磁杂质导致的自旋流

研究局域化磁性杂质引发的散射势对入射电子自旋取向的影响,该势可用Rashba哈密顿项表示.通过解薛定谔方程求得自旋空间的波函数,再由边界条件确定波函数的振幅,进而求出散射矩阵.应用buttiker理论,计算出通过磁性杂质引起的电流和自旋流,结果表明,在低温下,自旋流受电子库中所加磁场影响很小,而受费米能影响较大.     

XY自旋环境中量子比特纠缠动力学研究

利用精确解方法,研究了XY自旋环境中量子比特间纠缠随时问的演化．结果表明,系统纠缠度的演化可以通过改变自旋环境各向异性相互作用强度的方法得以操控．进而得出,可以利用各向异性相互作用对纠缠度演化行为的影响来判定自旋环境所属的普适类．     

磁调制量子结构的自旋过滤特性

基于杂化磁调制量子结构,我们从理论上提出了一电子自旋过滤器,并研究了其自旋输运性质.实验上,其可以通过在半导体异质结表面沉积磁化方向不同的铁磁条带形成.通过对真实InAs 材料系统的计算,发现这种系统具有很强的电子自旋极化效应,其自旋极化度在共振时几乎达到100%.因此,该结构可以用于电子自旋过滤器.     

通过自旋进动量子点的自旋相关的隧穿

Spin-polarized transport through a precessing magnetic spin coupled to ferromagnetic electrodes is studied using a non-equilibrium Green＇s function approach. The characteristic of conductance is obtained at zero temperature. We find that competition between spin-exchange interaction on the spin site and spin-orbit interaction in the barriers dominates the resonant behavior of conductance. In a parallel configuration, conductance peaks have identical amplitude. With the angle θ increasing, the width of resonant peaks is broadened or narrowed for different spin coherent states. In an anti-parallel case, spin-flip tunneling in the barriers will essentially enhance amplitude of the conductance peak.     

振荡磁场量子点中自旋流的交流响应

We investigate alternating response of the spin current in a quantum dot system coupled to a normal metal electrode,to which an alternating driving voltage and a pumping rotating magnetic field are applied.The expression of the time-averaged spin current and its differential is obtained based on a non-equilibrium Green's function method.We find that for a given rotating frequency,the spin current increases rapidly and appears to have small steps when the driven frequency increases.As the driven frequency is further increasing,the spin current can be significantly enhanced and approaches a stable value.The photon-assisted processes bring about interesting features of spin current.The influence of the gate voltage and temperature on the spin current is examined in detail.     

分步实现多态量子信息的传输

两游戏参与者Alice和Bob在进行二人零和量子硬币博弈时,游戏者之一Bob可以通过对盒子里的硬币采取量子策略的操作,干扰博弈的公平性结果,进而控制整个游戏的胜负.以此理论为基础,在量子链的格点处排布上合适初态的量子硬币,通过相应量子硬币“摇动”操作,分几步让量子链一端的信息传递到另一端,从而利用量子博弈理论为任意态量子信息的传输提供了一套全新的分步式方案,并且由于量子博弈不受经典操作的影响,所以在本方案信息传输的过程中大为降低了经典行为的干扰.     

通过带有调节器量子线的光场辅助隧穿

The paper studies photon-associated transmission through a quantum wire with a side-coupled stub tuner,to which an external microwave field applies,in terms of the approach developed by Cai.The inelastic scattering of an incoming electron and thd photon field lead to photon-electronic transmission though quantum wier.It is found that single photon absorbing (emitting) of the incoming electron in the stub can bring about antiresonant transmission in the quantum wire.The influence of the feedback mechanism from inelastic scattering process on elastic channel transmission is also examined.Total transmission coefficient as a function of photon energy exhibits non-periodic oscillation peaks.With the increasing of photon-electron coupling constant,the amplitude of these oscillation peaks enhances.     

GaAs量子环中类氢杂质能量的研究

利用B样条技术研究GaAs量子环中类氢杂质能量的量子尺寸效应.对计算结果比较看到：无磁场情况,对于｜m｜=0,r0〈75 nm,抛物禁闭关联势可以近似作为微扰项来处理;对于｜m｜≥0,r0〈60 nm,不可以采用微扰法.当r0〉90 nm时,库仑势可以近似作为微扰项来处理,但误差很大.当磁场B增加时,类氢杂质能量的量子尺寸效应出现明显变化,当r0〉90 nm时,量子环中类氢杂质能量快速上升.     

Aharonov-Casher Oscillasions of Transmission Through a Mesoscopic Ring with a Magnetic Impurity

Aharonov-Casher oscillasions of transmission through a mesoscopic ring with a magnetic impurity is investigated. Both spindependent transmission and reflection coefficients of spin-state electrons at zero-temperature are calculated as a function of the textured electric fields and its title angle in the present of spin-flipper scattering. It is found that the spin-exchange interaction can destroy intermittently periodic oscillations of spin-up transmission and reflection coefficients within some small ranges in the adiabatic region of quantum phase. However spin-down transmission and reflection coefficients appear periodic AC oscillations. The calculated results manifest that spindown transmission and reflection coefficients have the same perfect oscillation patterns. In the nonadiabatic region, the behavior of the anomalous AC oscillations are depedent on the difference between the tilt angle of spin and that of texture electric field.     

Conductance oscillations through an aharonov-bohm ring with a quantum gate

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通过带有量子门的Aharonov-Casher环的自旋极化电导振荡

1 Introduction Since some experi ments made by Yacoby,et al.[1],and Schuster ,et al.[2],that first measured electrontransmission phase through a quantum dot ( QD) ,phase sensitive transports in open mesoscopic ringwith a QD have been extensively investiga…     

量子点中强耦合磁极化子的尺寸和磁场效应

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定向量子余代数与其自身张量积上的定向量子余代数结构(英文)

定向量子代数(定向量子余代数)是拟三角Hopf代数(余拟三角Hopf代数)的推广并且可以得到定向1-1缠绕、定向扭结和连接的正则合痕不变量.令(H,σ,D,U)为域k上的定向量子余代数,则(H(×)H,ψ,D(×)D,U(×)U)为余代数H与其自身张量积上一个平凡的定向量子余代数结构,其中ψ(a(×)b,c(×)d)=ψ(a,c)ψ(b,d).本文给出余代数H H上的一种定向量子余代数结构(H(×)H,σ,D(×)D,U(×)U),其中σ(a b,c d)=σ-1(D1,a1)·σ(a2,c1)σ-1(d2,b1)σ(b2,c2).进一步得到定向量子余代数与其自身张量积上的一种非平凡的定向量子余代数结构,这一结果对偶于Radford发表于2007年的一文中的结论.理论上本文的结果对于构造定向扭结和连接不变量是非常重要的.     

利用量子化学软件分析分子器件上的电子输运性质

随着分子器件的测量和制备的技术不断突破,揭示电子输运机制的理论工作也得到了很大的发展。一些研究组分别发展了基于固体理论和量子化学的电子输运机制。实验证明,量子化学方法具有一定的优势。本文回顾了量子化学模拟方法的基本原理,并对其研究进展作了一个评述。