Exact propagation of open quantum systems in a system-reservoir context

TL;DR

This paper introduces an efficient stochastic method for exactly simulating open quantum systems with non-perturbative, non-Markovian, and driven dynamics, applicable to quantum information and thermodynamics.

Contribution

It reformulates a stochastic approach to handle finite reservoir correlations, enabling faster and more versatile simulations of complex open quantum systems.

Findings

Efficient simulation of spin-boson dynamics under strong driving.

Accurate modeling of Landau-Zener transitions in open systems.

Method surpasses previous techniques in computational efficiency.

Abstract

A stochastic representation of the dynamics of open quantum systems, suitable for non-perturbative system-reservoir interaction, non-Markovian effects and arbitrarily driven systems is presented. It includes the case of driving on timescales comparable to or shorter than the reservoir correlation time, a notoriously difficult but relevant case in the context of quantum information processing and quantum thermodynamics. A previous stochastic approach is re-formulated for the case of finite reservoir correlation and response times, resulting in a numerical simulation strategy exceeding previous ones by orders of magnitude in efficiency. Although the approach is based on a memory formalism, the dynamical equations propagated in the simulations are time-local. This leaves a wide range of choices in selecting the system to be studied and the numerical method used for propagation. For a series of tests, the dynamics of the spin-boson system is computed in various settings including strong external driving and Landau-Zener transitions.