论文标题
在静电浮动岛上超导子段状态的量子电容
Quantum capacitance of a superconducting subgap state in an electrostatically floating dot-island
论文作者
论文摘要
我们研究了在Inas纳米线中定义的混合设备，其外延壳由与超导岛接触的量子点组成。该设备是电浮动的，禁止运输测量值，但提供了对否则会非常兴奋和不稳定的状态的访问。射频反射仪与集体元件谐振器伴侣伴侣与量子点相对，并检测到离散子段状态的存在。我们对没有岛国的情况进行了详细的研究，但是由量子点诱导的子段状态由隧道耦合控制。当激发态的准核孔的间隙很小时，热激发的电容加载的电容会很大程度上抑制，这一效果是“热筛选”。可以使用单层安德森杂质模型来解释共振频移和质量因子的变化。已建立的测量方法以及分析和仿真框架适用于更复杂的混合设备，例如Andreev Molecules或Kitaev链。
We study a hybrid device defined in an InAs nanowire with an epitaxial Al shell that consists of a quantum dot in contact with a superconducting island. The device is electrically floating, prohibiting transport measurements, but providing access to states that would otherwise be highly excited and unstable. Radio-frequency reflectometry with lumped-element resonators couples capacitatively to the quantum dot, and detects the presence of discrete subgap states. We perform a detailed study of the case with no island states, but with quantum-dot-induced subgap states controlled by the tunnel coupling. When the gap to the quasi-continuum of the excited states is small, the capacitance loading the resonator is strongly suppressed by thermal excitations, an effect we dub "thermal screening". The resonance frequency shift and changes in the quality factor at charge transitions can be accounted for using a single-level Anderson impurity model. The established measurement method, as well as the analysis and simulation framework, are applicable to more complex hybrid devices such as Andreev molecules or Kitaev chains.
