Magnetic-field-dependent quasiparticle dynamics of nanowire single-Cooper-pair transistors

Magnetic-field-dependent quasiparticle dynamics of nanowire single-Cooper-pair transistors

van Veen, J. (TU Delft QuTech Advanced Research Centre; TU Delft QRD/Kouwenhoven Lab; Kavli institute of nanoscience Delft)
Proutski, A. (TU Delft QuTech Advanced Research Centre; TU Delft QRD/Geresdi Lab; Kavli institute of nanoscience Delft)
Karzig, Torsten (Microsoft Quantum Lab Delft)
Pikulin, D. (TU Delft QN/Theoretical Physics; Microsoft Quantum Lab Delft)
Lutchyn, Roman M. (Microsoft Quantum Lab Delft)
Nygård, Jesper (University of Copenhagen)
Krogstrup, P. (University of Copenhagen)
Geresdi, A. (TU Delft QuTech Advanced Research Centre; TU Delft QRD/Geresdi Lab; Kavli institute of nanoscience Delft)
Kouwenhoven, Leo P. (TU Delft QuTech Advanced Research Centre; TU Delft QRD/Kouwenhoven Lab; Kavli institute of nanoscience Delft; Microsoft Quantum Lab Delft)
Watson, J.D. (Microsoft Quantum Lab Delft)

2018

Parity control of superconducting islands hosting Majorana zero modes (MZMs) is required to operate topological qubits made from proximitized semiconductor nanowires. We test this control by studying parity effects in hybrid InAs-Al single-Cooper-pair transistors (SCPTs) to evaluate the feasibility of this material system. In particular, we investigate the gate-charge modulation of the supercurrent and observe a consistent 2e-periodic pattern indicating a general lack of low-energy subgap states in these nanowires at zero magnetic field. In a parallel magnetic field, an even-odd pattern develops with a gate-charge spacing that oscillates as a function of field demonstrating that the modulation pattern is sensitive to the presence of a single bound state. In addition, we find that the parity lifetime of the SCPT decreases exponentially with magnetic field as the bound state approaches zero energy. Our work shows that aluminum is the preferred superconductor for future topological qubit experiments and highlights the important role that quasiparticle traps and superconducting gap engineering would play in these qubits. Moreover, we demonstrate a means by which bound states can be detected in devices with superconducting leads.

http://resolver.tudelft.nl/uuid:b5ad08dd-0980-4712-b9d2-bd6b3e7100e5

https://doi.org/10.1103/PhysRevB.98.174502

2469-9950

Physical Review B, 98 (17)

Institutional Repository

journal article

© 2018 J. van Veen, A. Proutski, Torsten Karzig, D. Pikulin, Roman M. Lutchyn, Jesper Nygård, P. Krogstrup, A. Geresdi, Leo P. Kouwenhoven, J.D. Watson