Non-Hermitian phase-biased Josephson junctions

Jorge Cayao; Masatoshi Sato

doi:10.1103/PhysRevB.110.L201403

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Non-Hermitian phase-biased Josephson junctions

Jorge Cayao, Masatoshi Sato

DOI 10.1103/PhysRevB.110.L201403 · Physical Review B

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Abstract

We study non-Hermitian Josephson junctions formed by superconductors with a finite phase difference under non-Hermiticity, which naturally appears due to coupling to normal reservoirs. Depending on the structure of non-Hermiticity, captured in terms of retarded self-energies, the low-energy spectrum hosts topologically stable exceptional points either at zero or finite real energies as a function of the superconducting phase difference. Interestingly, the corresponding phase-biased supercurrents may acquire divergent profiles at such exceptional points. This instance is a natural and unique non-Hermitian effect that signals a possible way to enhance the sensitivity of Josephson junctions. Our work opens a way for realizing unique non-Hermitian phenomena due to the interplay between non-Hermitian topology and the Josephson effect.