Stochastic dressed wavefunction: a numerically exact solver for bosonic impurity model dynamics within wide time interval

TL;DR

This paper introduces a stochastic wavefunction method for simulating bosonic impurity model dynamics that efficiently handles emission and reabsorption processes over wide time intervals without sign problems.

Contribution

It presents a numerically exact solver combining stochastic emission simulation with bath discretization to accurately model impurity dynamics over extended periods.

Findings

Fast convergence with respect to bath sites

No sign problem in simulations

Applicable to wide time intervals

Abstract

In the dynamics of driven impurity models, there is a fundamental asymmetry between the processes of emission and absorption of environment excitations: most of the emitted excitations are rapidly and irreversibly scattered away, and only a small amount of them is reabsorbed back. We propose to use a stochastic simulation of the irreversible quantum emission processes in real-time dynamics, while taking into account the reabsorbed virtual excitations by the bath discretization. The resulting method delivers a fast convergence with respect to the number of bath sites, on a wide time interval, without the sign problem.