arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1206.3079cond-mat.mes-hallcond-mat.supr-con
收藏

手征对称性拓扑超导体的Andreev反射

Andreev reflection from a topological superconductor with chiral symmetry

M. Diez, J. P. Dahlhaus, M. Wimmer, C. W. J. Beenakker

摘要:

Tewari和Sau指出,<->N模超导导线中电子-空穴(e-h)激发的哈密顿量的手征对称性(H -&gt; -H if e h)与拓扑量子数\in \mathbb{Z}(对称类BDI)有关。这里我们证明了Q=Tr(r_{he})等于Andreev反射振幅矩阵的迹,提供了与电导G的联系。对于|Q| =N,N-1,我们导出了G=(2e^2/h)|Q|,并且更一般地给出了G的一个依赖于Q的上界和下界.我们在随机矩阵理论的圆形系综中计算了混沌散射的概率分布P(G),以获得弱局域化和介观电导波动的Q依赖性。在一个具有诱导超导性的无序半导体纳米线模型中,研究了横向动量的自旋-轨道耦合对手征对称性破缺的影响.对于小于自旋-轨道耦合长度的线宽度,电导作为化学势的函数可以表现出一系列2e^2/h的阶跃--对无序不敏感。

英文摘要:

It was pointed out by Tewari and Sau that chiral symmetry (H -> -H if e <-> h) of the Hamiltonian of electron-hole (e-h) excitations in an N-mode superconducting wire is associated with a topological quantum number Q\in\mathbb{Z} (symmetry class BDI). Here we show that Q=Tr(r_{he}) equals the trace of the matrix of Andreev reflection amplitudes, providing a link with the electrical conductance G. We derive G=(2e^2/h)|Q| for |Q|=N,N-1, and more generally provide a Q-dependent upper and lower bound on G. We calculate the probability distribution P(G) for chaotic scattering, in the circular ensemble of random-matrix theory, to obtain the Q-dependence of weak localization and mesoscopic conductance fluctuations. We investigate the effects of chiral symmetry breaking by spin-orbit coupling of the transverse momentum (causing a class BDI-to-D crossover), in a model of a disordered semiconductor nanowire with induced superconductivity. For wire widths less than the spin-orbit coupling length, the conductance as a function of chemical potential can show a sequence of 2e^2/h steps - insensitive to disorder.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑