Josephson ϕ0-junction in nanowire quantum dots
Abstract
The Josephson effect describes supercurrent flowing through a junction connecting two superconducting leads by a thin barrier. This current is driven by a superconducting phase difference ϕ between the leads. In the presence of chiral and time-reversal symmetry of the Cooper pair tunnelling process, the current is strictly zero when ϕ vanishes. Only if these underlying symmetries are broken can the supercurrent for ϕ = 0 be finite. This corresponds to a ground state of the junction being offset by a phase ϕ0, different from 0 or π. Here, we report such a Josephson ϕ0-junction based on a nanowire quantum dot. We use a quantum interferometer device to investigate phase offsets and demonstrate that ϕ0 can be controlled by electrostatic gating. Our results may have far-reaching implications for superconducting flux- and phase-defined quantum bits as well as for exploring topological superconductivity in quantum dot systems.
- Publication:
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Nature Physics
- Pub Date:
- June 2016
- DOI:
- 10.1038/nphys3742
- arXiv:
- arXiv:1512.01234
- Bibcode:
- 2016NatPh..12..568S
- Keywords:
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- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- Nat. Phys. 12 (2016) 568