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Quasi-adiabatic quantum Monte Carlo algorithm for quantum evolution in imaginary time

2013; American Physical Society; Volume: 87; Issue: 17 Linguagem: Inglês

10.1103/physrevb.87.174302

1550-235X

Chengwei Liu, Anatoli Polkovnikov, Anders W. Sandvik,

Theoretical and Computational Physics

We propose a quantum Monte Carlo (QMC) algorithm for nonequilibrium dynamics in a system with a parameter varying as a function of imaginary time. The method is based on successive applications of an evolving Hamiltonian to an initial state and delivers results for a whole range of the tuning parameter in a single run, allowing for access to both static and dynamic properties of the system. This approach reduces to the standard Schr\"odinger dynamics in imaginary time for quasi-adiabatic evolutions, i.e., including the leading nonadiabatic correction to the adiabatic limit. We here demonstrate this quasi-adiabatic QMC (QAQMC) method for linear ramps of the transverse-field Ising model across its quantum-critical point in one and two dimensions. The critical behavior can be described by generalized dynamic scaling. For the two-dimensional square-lattice system, we use the method to obtain a high-precision estimate of the quantum-critical point ${(h/J)}_{c}=3.04458(7)$, where $h$ is the transverse magnetic field and $J$ is the nearest-neighbor Ising coupling. The QAQMC method can also be used to extract the Berry curvature and the metric tensor.