Quantum Mpemba effect of Z2 symmetry restoration in the Dicke model

Abstract:We study a symmetry-restoration quantum Mpemba effect in the dissipative Dicke model as an example of a weakly $\mathbb Z_2$-symmetric open quantum system, where the full Liouvillian is parity covariant although individual quantum jumps connect the two Hilbert-space parity sectors. Using the entanglement-asymmetry (EA) diagnostic to monitor parity restoration, we compare coherent-product and cat-product initial states. Coherent-product states show conventional relaxation, with larger initial asymmetry decaying more slowly and no Mpemba crossing observed. Cat-product states, by contrast, can reverse this hierarchy over a finite region of initial-state space. This reversal is enabled by initial-state mode filtering: the cat-product superposition suppresses the contributions of the leading slow Liouvillian modes, allowing a more asymmetric state to restore parity through faster decay channels. Our results reveal that symmetry-restoration QME can arise even when parity is preserved only as a weak Liouvillian symmetry, with quantum jumps mixing the Hilbert-space parity sectors. The anomalous relaxation is governed by initial-state-dependent filtering of the leading slow Liouvillian modes, providing a mechanism for symmetry-restoration QME beyond strongly conserved symmetry sectors.

arXiv:2611.00902 [quant-ph]

(or arXiv:2611.00902v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2611.00902 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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