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Published June 2016 | Supplemental Material + Submitted
Journal Article Open

Josephson φ_0-junction in nanowire quantum dots


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 process2, 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 ϕ_0, 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 ϕ_0 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.

Additional Information

© 2016 Macmillan Publishers Limited. Received 30 November 2015; Accepted 23 March 2016; Published online 02 May 2016; Corrected online 02 September 2016. We gratefully acknowledge R. N. Schouten, S. M. Frolov, D. I. Pikulin, A. Geresdi, K. Zuo, V. Mourik, A. R. Akhmerov, M. Wimmer, Y. V. Nazarov and C. W. J. Beenakker for useful discussions and their help. This work has been supported by funding from the Netherlands Foundation for Fundamental Research on Matter (NWO/FOM), Microsoft Corporation Station Q and the ERC synergy grant. Author Contributions: D.B.S. fabricated the sample. D.B.S. and S.N.-P. performed the measurements. D.C., S.R.P. and E.P.A.M.B. grew the InSb nanowires. All authors discussed the data and contributed to the manuscript. The authors declare no competing financial interests.

Attached Files

Submitted - 1512.01234.pdf

Supplemental Material - nphys3742-s1.pdf


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