Quantum Mpemba effect in a four-site Bose-Hubbard model

We investigated the quantum Mpemba effect (QME) in a one-dimensional Bose-Hubbard model across clean and disordered regimes using exact numerical technique of a four-site lattice under Lindblad dynamics with local dephasing noise. By systematically varying hopping strength, onsite interactions, Stark potentials, and random disorder, we probe relaxation dynamics toward a common steady state using trace distance, relative entropy, entanglement asymmetry, and ₁-norm of coherence metrics. Our results reveal that QME emerges prominently in the clean-interacting regime, where many-body correlations drive nonlinear relaxation pathways, enabling initially distant states to overtake closer ones. In contrast, non-interacting systems exhibit conventional thermalization, whereas Stark potentials and random disorder suppress QME by inducing localization barriers, with disorder causing milder delays compared to the pronounced effects of Stark fields. Entanglement asymmetry proves to be particularly sensitive to the symmetry restoration dynamics underlying QME. These findings elucidate the critical role of interactions in anomalous relaxation and provide insights for controlling quantum thermalization in experimental platforms such as ultra-cold atomic systems.