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arXiv 1409.0986cond-mat.mes-hall
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正常-拓扑混合超导体Kondo模型中的输运

Transport in a hybrid normal-topological superconductor Kondo model

Razvan Chirla, I. V. Dinu, V. Moldoveanu, Catalin Pascu Moca

摘要:

我们研究了近藤机制中量子点的平衡和非平衡输运,该量子点嵌入在正常金属和拓扑超导体之间,在其端点处支持Majorana束缚态。我们发现,近藤物理显着修改的存在下的马约拉纳模式。当Majorana模耦合时,除了近藤尺度$T_K$之外,出现了一个新的能量尺度$T^*\ll T_K$,它控制着系统的低能物理。在低温下,对于低于$T^*$的频率,交流电导被抑制,而噪声频谱获得$\sim ω^3$依赖性。在高温下,$T \gg T_K$的微分电导中的规则对数依赖性也受到影响。在非平衡条件下,特别是在$\{T, B\}\to 0$极限下,微分电导变为负值。这些发现表明,在运输的变化可能作为线索,检测在这样的系统中的马约拉纳束缚态。在所使用的方法方面,我们通过微扰和重整化群的方法相结合的传输特性。

英文摘要:

We investigate the equilibrium and non-equilibrium transport through a quantum dot in the Kondo regime, embedded between a normal metal and a topological superconductor supporting Majorana bound states at its end points. We find that the Kondo physics is significantly modified by the presence of the Majorana modes. When the Majorana modes are coupled, aside from the Kondo scale $T_K$, a new energy scale $T^*\ll T_K$ emerges, that controls the low energy physics of the system. At low temperatures, the ac-conductance is suppressed for frequencies below $T^*$, while the noise spectrum acquires a $\sim ω^3$ dependence. At high temperatures, $T \gg T_K$, the regular logarithmic dependence in the differential conductance is also affected. Under non-equilibrium conditions, and in particular in the $\{T, B\}\to 0$ limit, the differential conductance becomes negative. These findings indicate that the changes in transport may serve as clues for detecting the Majorana bound states in such systems. In terms of methods used, we characterize the transport by using a combination of perturbative and renormalization group approaches.

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