Linear-algebraic bath transformation for simulating complex open quantum systems

TL;DR

This paper introduces a linear algebraic bath transformation that simplifies the simulation of complex open quantum systems by converting the star-bath model into multiple weakly-coupled chains, facilitating practical quantum simulations.

Contribution

A novel linear algebraic bath partition strategy that reduces system-bath coupling and transforms the star-bath into multiple weakly-coupled chains for improved simulation.

Findings

Enables practical quantum simulation of complex open systems.

Reduces system-bath coupling strength effectively.

Transforms star-bath into multiple parallel chains.

Abstract

In studying open quantum systems, the environment is often approximated as a collection of non-interacting harmonic oscillators, a configuration also known as the star-bath model. It is also well known that the star-bath can be transformed into a nearest-neighbor interacting chain of oscillators. The chain-bath model has been widely used in renormalization group approaches. The transformation can be obtained by recursion relations or orthogonal polynomials. Based on a simple linear algebraic approach, we propose a bath partition strategy to reduce the system-bath coupling strength. As a result, the non-interacting star-bath is transformed into a set of weakly-coupled multiple parallel chains. The transformed bath model allows complex problems to be practically implemented on quantum simulators, and it can also be employed in various numerical simulations of open quantum dynamics.