CUED Publications database

On-Chip Andreev Devices: Hard Superconducting Gap and Quantum Transport in Ballistic Nb–In0.75Ga0.25AsQuantum-Well–Nb Josephson Junctions

Delfanazari, K and Puddy, R and Ma, P and Yi, T and Cao, M and Gul, Y and Farrer, I and Ritchie, D and Joyce, H and Kelly, M and Smith, C (2017) On-Chip Andreev Devices: Hard Superconducting Gap and Quantum Transport in Ballistic Nb–In0.75Ga0.25AsQuantum-Well–Nb Josephson Junctions. Advanced Materials, 29. (Unpublished)

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Abstract

A superconducting hard gap in hybrid superconductor–semiconductor devices has been found to be necessary to access topological superconductivity that hosts Majorana modes (non-Abelian excitation). This requires the formation of homogeneous and barrier-free interfaces between the superconductor and semiconductor. Here, a new platform is reported for topological superconductivity based on hybrid Nb–In$_{0.75}$Ga$_{0.25}$As-quantum-well–Nb that results in hard superconducting gap detection in symmetric, planar, and ballistic Josephson junctions. It is shown that with careful etching, sputtered Nb films can make high-quality and transparent contacts to the In$_{0.75}$Ga$_{0.25}$As quantum well, and the differential resistance and critical current measurements of these devices are discussed as a function of temperature and magnetic field. It is demonstrated that proximity-induced superconductivity in the In$_{0.75}$Ga$_{0.25}$As-quantum-well 2D electron gas results in the detection of a hard gap in four out of seven junctions on a chip with critical current values of up to 0.2 µA and transmission probabilities of >0.96. The results, together with the large g-factor and Rashba spin–orbit coupling in In$_{0.75}$Ga$_{0.25}$As quantum wells, which indeed can be tuned by the indium composition, suggest that the Nb–In$_{0.75}$Ga$_{0.25}$As–Nb system can be an excellent candidate to achieve topological phase and to realize hybrid topological superconducting devices.

Item Type: Article
Uncontrolled Keywords: Josephson junctions hybrid superconductor-semiconductor junctions quantum computing topological superconductivity
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:09
Last Modified: 24 Nov 2020 11:37
DOI: 10.1002/adma.201701836