Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, 28049 Madrid, Spain.
Phys Rev Lett. 2018 Sep 21;121(12):127705. doi: 10.1103/PhysRevLett.121.127705.
We study transport mediated by Andreev bound states formed in InSb nanowire quantum dots. Two kinds of superconducting source and drain contacts are used: epitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while, in NbTiN/InSb devices, Andreev spectra of the dot appear to be replicated multiple times at increasing source-drain bias voltages. In both devices, a mirage of a crowded spectrum is created. To describe the observations a model is developed that combines the effects of a soft induced gap and of additional Andreev bound states both in the quantum dot and in the finite regions of the nanowire adjacent to the quantum dot. Understanding of Andreev spectroscopy is important for the correct interpretation of Majorana experiments done on the same structures.
我们研究了由 InSb 纳米线量子点中形成的安德烈夫束缚态介导的输运。使用了两种超导源和漏接触：外延 Al/InSb 器件表现出隧道共振的加倍，而在 NbTiN/InSb 器件中，点的安德烈夫谱似乎在源-漏偏压增加时多次复制。在这两种器件中，都会产生密集谱的幻象。为了描述观察结果，我们开发了一个模型，该模型结合了软诱导能隙的影响以及量子点中和量子点相邻的纳米线有限区域中的附加安德烈夫束缚态的影响。对安德烈夫光谱学的理解对于正确解释在相同结构上进行的马约拉纳实验非常重要。
