Nonequilibrium phase transition of dissipative fermionic superfluids: Case study of multi-terminal Josephson junctions

Abstract:We investigate nonequilibrium dynamics of a triad of fermionic superfluids connected via Josephson junctions, following sudden switch-on of two-body loss in one of the three superfluids. By formulating the dissipative BCS theory for the Lindblad equation, we find that the superfluid order parameter exhibits a phase rotation, thereby giving rise to three types of dc Josephson currents corresponding to different junctions. We demonstrate that, when the tunneling amplitude $V_{31}$ between superfluids without two-body loss is weak, a two-step nonequilibrium phase transition characterized by the vanishing dc Josephson currents occurs: dissipation first induces the nonequilibrium phase transition by making one dc Josephson current finite, while further increasing dissipation makes this remaining dc Josephson current vanish. By contrast, when $V_{31}$ is strong, dissipation induces the nonequilibrium phase transition in which all dc Josephson currents simultaneously vanish. An analytical study based on a simplified model further supports this observation.

Quantum Gases (cond-mat.quant-gas); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)

arXiv:2604.00574 [cond-mat.quant-gas]

(or arXiv:2604.00574v2 [cond-mat.quant-gas] for this version)

https://doi.org/10.1103/r9gx-gy1s DOI(s) linking to related resources