Non-Hermiticity of an anomalous superradiant phase

• URL: http://arxiv.org/abs/2606.26770v1
• Date: Thu, 25 Jun 2026 08:54:29 GMT
• Title: Non-Hermiticity of an anomalous superradiant phase
• Abstract summary: We present a Hermitian squeezing-Dicke model as a minimal setting for non-Hermitian physics in many-body light-matter systems.<n>Our system offers an alternative pathway to exotic non-Hermitian physics and nonreciprocal quantum amplification.
• Score: 5.735398718880578
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We counterintuitively present a Hermitian squeezing-Dicke model as a minimal setting for non-Hermitian physics in many-body light-matter systems. It enables the realization of a non-Hermitian Hamiltonian of interest using a Hermitian quadratic bosonic system. Unlike previous dissipation-driven non-Hermitian mechanisms, effective parity-time ($\mathcal{PT}$) symmetry arises purely from squeezing and exchanges gainy and lossy eigenmodes. We identify non-Hermiticity of an anomalous superradiant phase for strong spins squeezing, exhibiting spontaneous breaking of the unique $\mathcal{PT}$ symmetry beyond $Z_2$ symmetries. Such exotic phase exhibits a complex excitation spectrum and undergoes a dynamical phase transition to a conventional superradiant phase at an exceptional point. An artificial magnetic field combined with the broken Hermiticity yields nonreciprocal dynamics with striking quantum amplification, exhibiting unidirectional enhanced transmission. Our Hermitian light-matter system offers an alternative pathway to exotic non-Hermitian physics and nonreciprocal quantum amplification.

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