Control and detection of Majorana bound states in quantum dot arrays
Control and detection of Majorana bound states in quantum dot arrays
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DOI：
10.1103/physrevb.98.085407
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发表时间：
2018-05
影响因子：
3.7
通讯作者：
John P. T. Stenger;B. Woods;S. Frolov;T. Stanescu
中科院分区：
文献类型：
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作者：
John P. T. Stenger;B. Woods;S. Frolov;T. Stanescu
我们研究了通过将半导体纳米线邻近耦合到由狭窄的未覆盖区域分隔的多个超导岛来实现的一维超导量子点阵列的低能物理。量子点和未覆盖区域内的有效静电势可以使用势门控制。通过基于有效的紧束缚模型进行详细的数值计算，我们发现由部分重叠的马约拉纳束缚态组成的多个低能亚能隙态通常出现在未覆盖区域的附近。显式微分电导计算表明，稳健的零偏置电导峰值与整个系统中局部存在的此类状态并不不一致，因此，对此类峰值的观察并不能证明实现了良好分离的马约拉纳零模式。然而，我们发现，在未覆盖的区域中创建有效势阱会捕获附近部分重叠的马约拉纳束缚态对，这些束缚态的分离程度会降低，并获得有限的间隙，以保护位于系统末端的一对马约拉纳零模。这种行为在一个重要的参数范围内持续存在，表明邻近的量子点阵列可以为高度可控的马约拉纳设备提供一个平台。
We study the low-energy physics of a one-dimensional array of superconducting quantum dots realized by proximity coupling a semiconductor nanowire to multiple superconducting islands separated by narrow uncovered regions. The effective electrostatic potential inside the quantum dots and the uncovered regions can be controlled using potential gates. By performing detailed numerical calculations based on effective tight-binding models, we find that multiple low-energy subgap states consisting of partially overlapping Majorana bound states emerge generically in the vicinity of the uncovered regions. Explicit differential conductance calculations show that a robust zero-bias conductance peak is not inconsistent with the presence of such states localized throughout the system, hence, the observation of such a peak does not demonstrate the realization of well-separated Majorana zero modes. However, we find that creating effective potential wells in the uncovered regions traps pairs of nearby partially overlapping Majorana bound states, which become less separated and acquire a finite gap that protects the pair of Majorana zero modes localized at the ends of the system. This behavior persists over a significant parameter range, suggesting that proximitized quantum dot arrays could provide a platform for highly controllable Majorana devices.