Subtle leakage of a Majorana mode into a quantum dot
Subtle leakage of a Majorana mode into a quantum dot
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DOI：
10.1103/physrevb.89.165314
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发表时间：
2013-08
影响因子：
3.7
通讯作者：
E. Vernek;P. Penteado;A. Seridonio;J. C. Egues
中科院分区：
文献类型：
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作者：
E. Vernek;P. Penteado;A. Seridonio;J. C. Egues
我们研究了通过连接到源极和漏极引线并侧面耦合到支持Majorana端模的拓扑超导纳米线(Kitaev链)的量子点的量子输运。利用递归格林函数方法，我们确定了系统的局域态密度，发现导线的末端Majorana模泄漏到点中，从而出现了钉扎在引线的费米能量EF上的唯一点能级。令人惊讶的是，即使在栅极控制的网点电平(VG)远高于或远低于EF的情况下，这种共振钉扎也会发生，从这个意义上说，它类似于“近藤共振”。计算的点的电导G显示了导线的Majorana端模式的明确签名：本质上，应具有G=0的非共振点[eDot(VG)�Ef]由于这种钉扎点模式而在VG的大范围内显示电导e2/2h。有趣的是，只有当点水平耦合到Majorana模式时，这种钉扎效应才会发生；导线中的普通费米子模式(例如，无序)只是简单地分裂和加宽(如果是连续体)点水平。我们讨论了通过这些泄漏/钉扎的点模式来探测导线中的Majorana模式的实验场景。
We investigate quantum transport through a quantum dot connected to source and drain leads and side coupled to a topological superconducting nanowire (Kitaev chain) sustaining Majorana end modes. Using a recursive Green’s-function approach, we determine the local density of states of the system and find that the end Majorana mode of the wire leaks into the dot, thus, emerging as a unique dot level pinned to the Fermi energy eF of the leads. Surprisingly, this resonance pinning, resembling, in this sense, a “Kondo resonance,” occurs even when the gate-controlled dot level edot(Vg) is far above or far below eF . The calculated conductance G of the dot exhibits an unambiguous signature for the Majorana end mode of the wire: In essence, an off-resonance dot [edot(Vg) � eF ], which should have G = 0, shows, instead, a conductance e 2 /2h over a wide range of Vg due to this pinned dot mode. Interestingly, this pinning effect only occurs when the dot level is coupled to a Majorana mode; ordinary fermionic modes (e.g., disorder) in the wire simply split and broaden (if a continuum) the dot level. We discuss experimental scenarios to probe Majorana modes in wires via these leaked/pinned dot modes.