Exact stochastic simulation of dissipation and non-Markovian effects in open quantum systems

TL;DR

This paper introduces an exact stochastic method for simulating the dynamics of open quantum systems, capturing dissipation and non-Markovian effects without approximations, applicable to models like the spin-boson system.

Contribution

It presents a novel exact stochastic approach that incorporates environment effects through a non-local, stochastic mean-field, enabling precise simulation of open quantum system dynamics.

Findings

Successfully applied to the spin-boson model across various regimes

Captures dissipative and non-Markovian effects exactly

Links to stochastic Schrödinger equations and potential for imaginary time extensions

Abstract

The exact dynamics of a system coupled to an environment can be described by an integro-differential stochastic equation of its reduced density. The influence of the environment is incorporated through a mean-field which is both stochastic and non-local in time and where the standard two-times correlation functions of the environment appear naturally. Since no approximation is made, the presented theory incorporates exactly dissipative and non-Markovian effects. Applications to the spin-boson model coupled to a heat-bath with various coupling regimes and temperature show that the presented stochastic theory can be a valuable tool to simulate exactly the dynamics of open quantum systems. Links with stochastic Schroedinger equation method and possible extensions to "imaginary time" propagation are discussed.