First-Order PT Phase Transition in Non-Hermitian Superconductors

Abstract: The interplay between superconductivity and environmental dissipation, effectively captured by non-Hermitian Hamiltonian, is a new frontier for exotic quantum phases. We explore a PT-symmetric non-Hermitian superconductor with balanced gain and loss. To ensure experimental relevance, we develop a right-eigenstate-based non-Hermitian mean-field theory. We uncover a novel first-order phase transition that coincides exactly with the PT symmetry breaking point, driven by the interplay between superconducting pairing interactions and non-Hermitian dissipation. In the PT-symmetric phase, moderate NH dissipation enhances superconductivity, while in the PT-broken phase, intensified dissipation significantly suppresses it. These phenomena, characterized by abrupt jumps in observables, can be probed through localized spectral measurements and macroscopic superfluid density analysis. Additionally, the stability analysis offers robust theoretical insights to support experimental investigations of this unique transition.