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arXiv · 2507.22583

Non-Hermitian Quantum Many-Body Scar Phase

Keita Omiya·Yuya O Nakagawa
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Abstract

We introduce a novel non-equilibrium phase -- the quantum many-body scar (QMBS) phase -- that emerges in non-Hermitian many-body dynamics when scarred wavefunctions are selectively stabilized via non-Hermitian driving. Projective measurements, or non-Hermitian counterparts, preferentially reinforce QMBS, counteracting the entropy growth that drives thermalization. As a result, atypical, high-energy scarred wavefunctions that are negligible in the long-time dynamics of closed systems become non-equilibrium steady states. We establish the existence of the QMBS phase and its sharp, first-order phase transition from an ergodic thermal phase, through both analytical arguments and numerical simulations of three representative models: a random quantum circuit model, the $SU(q)$ spin model, and the paradigmatic spin-1 XY model.

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Keita Omiya, Yuya O Nakagawa. 2025-07-30. Non-Hermitian Quantum Many-Body Scar Phase. https://arxiv.org/abs/2507.22583

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