• Accepted Paper

Symmetry restoration and quantum Mpemba effect in the complex Sachdev-Ye-Kitaev model

Sizheng Cao and Xian-Hui Ge

Phys. Rev. B - Accepted 29 October, 2026

DOI: https://doi.org/10.1103/lk1h-6769

Abstract

Entanglement asymmetry, used here as a direct probe of symmetry restoration, provides a sharp diagnostic of post-quench dynamics. We test this idea in the complex Sachdev-Ye-Kitaev model with a conserved U(1) charge. We numerically track the joint evolution of entanglement entropy and entanglement asymmetry after quenches from charge asymmetric product states. We find rapid volume law entanglement growth and late time subsystem equilibration in the cSYK dynamics, accompanied by a concurrent decay of entanglement asymmetry to a late time plateau set by finite size effects: small subsystems display near complete restoration, while residual cross sector weight yields a finite plateau. For the system sizes, initial states, and parameters studied, the cSYK model exhibits faster entanglement growth and subsystem symmetry restoration than the XXZ model and a spin-polarized one-dimensional fermion chain after a common energy scale normalization. In the disorder averaged cSYK dynamics, tilted ferromagnetic states with larger initial asymmetry can relax faster and reach lower late time asymmetry plateaus, exhibiting the quantum Mpemba effect. No crossing of the entanglement asymmetry curves is observed for tilted N´eel states within the same parameter window. We further derive a Pinsker-type lower bound relating entanglement asymmetry to the purity difference between the reduced density matrix and its U(1) dephased counterpart. These results highlight entanglement asymmetry as a probe of subsystem symmetry restoration and characterize the residual asymmetry at finite sizes in the cSYK model.

Export citation

Export citation

Choose format for download:

Download Citation

If the author has provided any supplemental materials with this article they will be available upon publication of the version of record.

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation