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Title: Current–phase relations of few-mode InAs nanowire Josephson junctions

Gate-tunable semiconductor nanowires with superconducting leads have great potential for quantum computation and as model systems for mesoscopic Josephson junctions. The supercurrent, I, versus the phase, Φ, across the junction is called the current–phase relation (CPR). It can reveal not only the amplitude of the critical current, but also the number of modes and their transmission. Here, we measured the CPR of many individual InAs nanowire Josephson junctions, one junction at a time. Both the amplitude and shape of the CPR varied between junctions, with small critical currents and skewed CPRs indicating few-mode junctions with high transmissions. In a gate-tunable junction, we found that the CPR varied with gate voltage: near the onset of supercurrent, we observed behaviour consistent with resonant tunnelling through a single, highly transmitting mode. The gate dependence is consistent with modelled subband structure that includes an effective tunnelling barrier due to an abrupt change in the Fermi level at the boundary of the gate-tuned region. These measurements of skewed, tunable, few-mode CPRs are promising both for applications that require anharmonic junctions and for Majorana readout proposals.
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [4] ;  [4] ;  [5]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES); Stanford Univ., CA (United States). Dept. of Physics
  2. Univ. of Copenhagen (Denmark). The Niels Bohr Inst., Center for Quantum Devices and Station Q Copenhagen; National Univ. of Defense Technology (NUDT), Changsha (China). State Key Lab. of High Performance Computing
  3. Univ. of Copenhagen (Denmark). The Niels Bohr Inst., Center for Quantum Devices and Station Q Copenhagen; Freie Univ., Berlin (Germany). Dept. of Physics
  4. Univ. of Copenhagen (Denmark). The Niels Bohr Inst., Center for Quantum Devices and Station Q Copenhagen
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES); Stanford Univ., CA (United States). Dept. of Physics; Stanford Univ., CA (United States). Dept. of Applied Physics
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Nature Physics
Additional Journal Information:
Journal Volume: 13; Journal Issue: 12; Journal ID: ISSN 1745-2473
Publisher:
Nature Publishing Group (NPG)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Danish National Research Foundation; Lundbeck Foundation; Carlsberg Foundation; European Commission (EC)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Superconducting devices; Superconducting properties and materials
OSTI Identifier:
1419942

Spanton, Eric M., Deng, Mingtang, Vaitiekėnas, Saulius, Krogstrup, Peter, Nygård, Jesper, Marcus, Charles M., and Moler, Kathryn A.. Current–phase relations of few-mode InAs nanowire Josephson junctions. United States: N. p., Web. doi:10.1038/nphys4224.
Spanton, Eric M., Deng, Mingtang, Vaitiekėnas, Saulius, Krogstrup, Peter, Nygård, Jesper, Marcus, Charles M., & Moler, Kathryn A.. Current–phase relations of few-mode InAs nanowire Josephson junctions. United States. doi:10.1038/nphys4224.
Spanton, Eric M., Deng, Mingtang, Vaitiekėnas, Saulius, Krogstrup, Peter, Nygård, Jesper, Marcus, Charles M., and Moler, Kathryn A.. 2017. "Current–phase relations of few-mode InAs nanowire Josephson junctions". United States. doi:10.1038/nphys4224. https://www.osti.gov/servlets/purl/1419942.
@article{osti_1419942,
title = {Current–phase relations of few-mode InAs nanowire Josephson junctions},
author = {Spanton, Eric M. and Deng, Mingtang and Vaitiekėnas, Saulius and Krogstrup, Peter and Nygård, Jesper and Marcus, Charles M. and Moler, Kathryn A.},
abstractNote = {Gate-tunable semiconductor nanowires with superconducting leads have great potential for quantum computation and as model systems for mesoscopic Josephson junctions. The supercurrent, I, versus the phase, Φ, across the junction is called the current–phase relation (CPR). It can reveal not only the amplitude of the critical current, but also the number of modes and their transmission. Here, we measured the CPR of many individual InAs nanowire Josephson junctions, one junction at a time. Both the amplitude and shape of the CPR varied between junctions, with small critical currents and skewed CPRs indicating few-mode junctions with high transmissions. In a gate-tunable junction, we found that the CPR varied with gate voltage: near the onset of supercurrent, we observed behaviour consistent with resonant tunnelling through a single, highly transmitting mode. The gate dependence is consistent with modelled subband structure that includes an effective tunnelling barrier due to an abrupt change in the Fermi level at the boundary of the gate-tuned region. These measurements of skewed, tunable, few-mode CPRs are promising both for applications that require anharmonic junctions and for Majorana readout proposals.},
doi = {10.1038/nphys4224},
journal = {Nature Physics},
number = 12,
volume = 13,
place = {United States},
year = {2017},
month = {8}
}