Non-Hermiticity of an anomalous superradiant phase
Abstract
We present a Hermitian squeezing-Dicke model as a minimal closed-system setting for non-Hermitian many-body physics. Squeezing generates an effective parity-time (π«π―) symmetry and exchanges gainy and lossy eigenmodes without dissipation. We identify an anomalous dynamical superradiant phase (DSRP) that exhibits by a mean-field superradiant order in the π«π― symmetry-breaking regime, accompanied by a β€2-symmetry-breaking ground-state quantum phase transition. Additionally, it undergoes a π«π―-breaking dynamical phase transition at an exceptional point (EP). The excitation energy vanishes near both boundaries, giving critical slowing down. The vacuum photon number is divergent at the ground-state transition but is finite and nonanalytic at the EP, distinguishing the DSRP from the conventional superradiant phase and from a standard dynamical instability. Squeezing causes the coupling phase to act as an artificial magnetic flux, which yields flux-controlled nonreciprocal quantum amplification in the DSRP. Our results offer an alternative pathway to non-Hermitian many-body physics and nonreciprocal quantum amplification in closed Hermitian systems.
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BibTeX
@misc{lu2026nonhermiticity,
title = {{Non-Hermiticity of an anomalous superradiant phase}},
author = {You-Qi Lu and Jun-Ling Wang and Qing-Hu Chen and Yu-Yu Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.26770},
eprint = {2606.26770},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.26770},
}
RIS
TY - UNPB
TI - Non-Hermiticity of an anomalous superradiant phase
AU - You-Qi Lu
AU - Jun-Ling Wang
AU - Qing-Hu Chen
AU - Yu-Yu Zhang
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2606.26770
UR - https://arxiv.org/abs/2606.26770
AB - We present a Hermitian squeezing-Dicke model as a minimal closed-system setting for non-Hermitian many-body physics. Squeezing generates an effective parity-time (π«π―) symmetry and exchanges gainy and lossy eigenmodes without dissipation. We identify an anomalous dynamical superradiant phase (DSRP) that exhibits by a mean-field superradiant order in the π«π― symmetry-breaking regime, accompanied by a β€_2-symmetry-breaking ground-state quantum phase transition. Additionally, it undergoes a π«π―-breaking dynamical phase transition at an exceptional point (EP). The excitation energy vanishes near both boundaries, giving critical slowing down. The vacuum photon number is divergent at the ground-state transition but is finite and nonanalytic at the EP, distinguishing the DSRP from the conventional superradiant phase and from a standard dynamical instability. Squeezing causes the coupling phase to act as an artificial magnetic flux, which yields flux-controlled nonreciprocal quantum amplification in the DSRP. Our results offer an alternative pathway to non-Hermitian many-body physics and nonreciprocal quantum amplification in closed Hermitian systems.
ER -