Conductance asymmetries in mesoscopic superconducting devices due to finite bias

Journal Article (2021)
Author(s)

André De Almeida Nascimento e Melo (TU Delft - QN/Akhmerov Group, Kavli institute of nanoscience Delft)

C. Liu (TU Delft - QRD/Wimmer Group, TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft)

P.M. Rozek (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QRD/Wimmer Group)

Tomas Orn Rosdahl (Kavli institute of nanoscience Delft, TU Delft - QRD/Wimmer Group)

M.T. Wimmer (Kavli institute of nanoscience Delft, TU Delft - QRD/Wimmer Group, TU Delft - QuTech Advanced Research Centre)

Research Group
QRD/Wimmer Group
Copyright
© 2021 A.A. De Almeida Nascimento e Melo, C. Liu, P.M. Rozek, T.O. Rosdahl, M.T. Wimmer
DOI related publication
https://doi.org/10.21468/SCIPOSTPHYS.10.2.037
More Info
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Publication Year
2021
Language
English
Copyright
© 2021 A.A. De Almeida Nascimento e Melo, C. Liu, P.M. Rozek, T.O. Rosdahl, M.T. Wimmer
Research Group
QRD/Wimmer Group
Issue number
2
Volume number
10
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Abstract

Tunneling conductance spectroscopy in normal metal-superconductor junctions is an important tool for probing Andreev bound states in mesoscopic superconducting devices, such as Majorana nanowires. In an ideal superconducting device, the subgap conductance obeys specific symmetry relations, due to particle-hole symmetry and unitarity of the scattering matrix. However, experimental data often exhibits deviations from these symmetries or even their explicit breakdown. In this work, we identify a mechanism that leads to conductance asymmetries without quasiparticle poisoning. In particular, we investigate the effects of finite bias and include the voltage dependence in the tunnel barrier transparency, finding significant conductance asymmetries for realistic device parameters. It is important to identify the physical origin of conductance asymmetries: in contrast to other possible mechanisms such as quasiparticle poisoning, finite-bias effects are not detrimental to the performance of a topological qubit. To that end we identify features that can be used to experimentally determine whether finite-bias effects are the source of conductance asymmetries.