Dynamical recovery of SU(2) symmetry in the mass-quenched Hubbard model

Abstract

We use non-equilibrium dynamical mean-field theory with iterative perturbation theory as an impurity solver to study the recovery of SU (2) symmetry in real-time following a hopping integral parameter quench from a mass-imbalanced to a mass-balanced single-band Hubbard model at half-filling. A dynamical order parameter γ(t) is defined to characterize the evolution of the system towards SU (2) symmetry. By comparing the momentum dependent occupation from an equilibrium calculation (with the SU (2) symmetric Hamiltonian after the quench at an effective temperature) with the data from our non-equilibrium calculation, we conclude that the SU (2) symmetry recovered state is a thermalized state. Further evidence from the evolution of the density of states supports this conclusion. At the same time, we find the order parameter in the weak Coulomb interaction regime undergoes an approximate exponential decay. We numerically investigate the interplay of the relevant parameters (initial temperature, Coulomb interaction strength, initial mass-imbalance ratio) and their combined effect on the thermalization behavior. Finally, we study evolution of the order parameter as the hopping parameter is changed with either a linear ramp or a pulse. Our results can be useful in strategies to engineer the relaxation behavior of interacting, quantum many-particle systems.

One-dimensional repulsive Hubbard model with mass imbalance: Orders and filling anomaly

“…However, the predicted spin gap physics has not been observed numerically for systems away from commensurate filling [25]. On the other hand, crystallization was found at both 1/2 [26] and 1/3 filling [25].…”

Flow Equation Approach to Periodically Driven Quantum Systems

“…The existence of a prethermal regime is important because realistic systems usually contain integrabilitybreaking perturbations that support it, and because the thermalization (or more specifically, the energy absorption) time τ can correspond to experimentally accessible time scales. The existence of such a regime also implies that there is interesting physics to be found at intermediate times 0 < t < τ [52,59], where one may use timedependent perturbations to drive dynamical phase transitions [60][61][62][63], control interactions [64,65], or engineer phase transitions and topological phases [66][67][68][69][70].…”