Nonequilibrium variational cluster perturbation theory: Quench dynamics of the quantum Ising model

Article

关键词: ENERGY-FUNCTIONAL APPROACH;    DUAL-FERMION APPROACH;    TRANSVERSE FIELD;    HUBBARD-MODEL;    SELF-ENERGY;    RENORMALIZATION-GROUP;    EXPANSION;    SYSTEMS;    DIAGRAM;    PHASE;   

DOI  :  10.1103/PhysRevB.94.205146

来源: SCIE

【 摘 要 】

We introduce a variational implementation of cluster perturbation theory (CPT) to address the dynamics of spin systems driven out of equilibrium. We benchmark the method with the quantum Ising model subject to a sudden quench of the transverse magnetic field across the transition or within a phase. We treat both the one-dimensional case, for which an exact solution is available, as well the two-dimensional case, for which we have to resort to numerical results. Comparison with exact results shows that the approach provides a quite accurate description of the real-time dynamics up to a characteristic timescale tau that increases with the size of the cluster used for CPT. In addition, and not surprisingly, tau is small for quenches across the equilibrium phase transition point, but can be quite larger for quenches within the ordered or disordered phases.

【 授权许可】

Free