Stochastic Wave-Function Simulation of Irreversible Emission Processes for Open Quantum Systems in a Non-Markovian Environment

TL;DR

This paper introduces a stochastic wave-function simulation method for modeling irreversible emission processes in open quantum systems within non-Markovian environments, enabling efficient long-time dynamics analysis.

Contribution

The authors developed an exact simulation approach for quantum emission with approximate backaction, addressing the sign problem and enabling long-time non-Markovian quantum transport simulations.

Findings

Successfully simulated Kondo cloud dynamics after a quench.

Achieved efficient real-time simulation of small quantum systems in non-Markovian baths.

Demonstrated the method's ability to reach quasistationary regimes.

Abstract

When conducting the numerical simulation of quantum transport, the main obstacle is a rapid growth of the dimension of entangled Hilbert subspace. The Quantum Monte Carlo simulation techniques, while being capable of treating the problems of high dimension, are hindered by the so-called "sign problem". In the quantum transport, we have fundamental asymmetry between the processes of emission and absorption of environment excitations: the emitted excitations are rapidly and irreversibly scattered away. Whereas only a small part of these excitations is absorbed back by the open subsystem, thus exercising the non-Markovian self-action of the subsystem onto itself. We were able to devise a method for the exact simulation of the dominant quantum emission processes, while taking into account the small backaction effects in an approximate self-consistent way. Such an approach allows us to efficiently conduct simulations of real-time dynamics of small quantum subsystems immersed in non-Markovian bath for large times, reaching the quasistationary regime. As an example we calculate the spatial quench dynamics of Kondo cloud for a bozonized Kodno impurity model.