English

Quantum Mpemba effect in long-ranged U(1)-symmetric random circuits

Quantum Physics 2025-12-09 v1

Abstract

The Mpemba effect, where a state prepared farther from equilibrium relaxes faster to equilibrium than one prepared closer, has a quantum counterpart where relaxation is resolved by conserved charge. However, the fate of the quantum Mpemba effect in systems with long-range interactions remains an open question. Here, we study the quantum Mpemba effect in long-ranged, U(1)-symmetric random unitary circuits. Using annealed R\'enyi-2 entanglement asymmetry computed via replica tensor networks and exact diagonalization, we track the symmetry restoration from three types of tilted product states: ferromagnetic, antiferromagnetic, and ferromagnetic with a central domain wall. The quantum Mpemba effect is present for tilted ferromagnetic states at all interaction ranges, but absent for tilted antiferromagnetic states, and occurs for the domain-wall state only in effectively short-ranged circuits, where the Mpemba time tMt_{\rm M} is found to scale with the subsystem size NAN_A as tM ⁣ ⁣NAzt_{\rm M}\!\sim\!N_{A}^{\,z}, with the dynamical exponent z=min(α1,2)z=\min(\alpha-1,2). These results reveal how the quantum Mpemba effect is governed by the interplay between interaction range and initial-state charge bias in long-ranged chaotic systems.

Keywords

Cite

@article{arxiv.2512.06775,
  title  = {Quantum Mpemba effect in long-ranged U(1)-symmetric random circuits},
  author = {Han-Ze Li and Ching Hua Lee and Shuo Liu and Shi-Xin Zhang and Jian-Xin Zhong},
  journal= {arXiv preprint arXiv:2512.06775},
  year   = {2025}
}
R2 v1 2026-07-01T08:13:35.135Z