Quantum Monte Carlo simulation of the dynamics of the spin-boson model

Olga Goulko, Guy Cohen, Moshe Goldstein +1 more

Olga Goulko, Guy Cohen, Moshe Goldstein

A. Lücke, Reinhold Egger, Lothar Mühlbacher +1 more

Chi H. Mak, David Chandler

A method of solving the sign problem in the Monte Carlo path-integral simulations of quantum dynamics is presented. Our method is based on the distortion of integration contours in conjunction with a stationary-phase-filtering method. Using this importance sampling, correlation functions for the spin-boson model have been computed for real times much longer than \ensuremath{\beta}\ensuremath{\Elzxh}.

Arnim Lück, Manfred Winterstetter, Ulrich Weiß +1 more

A discretized path integral formulation of the real-time dynamics applicable to a general external field is derived for the driven spin-boson model to extend the recently developed real-time Quantum Monte Carlo algorithm to driven systems. Numerical results are obtained for a monochromatic periodic driving force and Ohmic dissipation with a high-frequency cutoff. The impact of an external driving field on the dissipative dynamics is examined for systems with a time-dependent bias as well as a time-dependent interstate coupling matrix element. This method is easily generalized to multistate tight-binding models.

Manuel Weber

We present an exact quantum Monte Carlo method for spin systems coupled to dissipative bosonic baths which makes use of nonlocal wormhole updates to simulate the retarded spin-flip interactions originating from an off-diagonal spin-boson coupling. The method is closely related to the stochastic series expansion and extends the scope of the global directed-loop updates to nonlocal moves through a world-line configuration. We test our method for the U(1)-symmetric two-bath spin-boson model, where the off-diagonal components of a spin-1/2 particle are coupled to identical independent baths with power-law spectra, and get a precise estimate of the critical coupling between the critical and the localized phase. Our method applies to impurity systems and lattice models in any spatial dimension coupled to bosonic modes with arbitrary spectral distributions.