Modeling the unphysical pseudomode model with physical ensembles: simulation, mitigation, and restructuring of non-Markovian quantum noise

TL;DR

This paper proposes a method to simulate unphysical pseudomode models of non-Markovian quantum noise using physical ensembles, enabling better quantum simulations, noise mitigation, and bath restructuring.

Contribution

It introduces an extrapolation technique to reproduce unphysical pseudomode effects with physical systems, facilitating advanced quantum simulations and noise control.

Findings

Effective simulation of non-Markovian environments using physical ensembles.

Mitigation of unwanted non-Markovian noise in quantum devices.

Ability to restructure properties of physical baths, such as temperature.

Abstract

The influence of a Gaussian environment on a quantum system can be described by effectively replacing the continuum with a discrete set of ancillary quantum and classical degrees of freedom. This defines a pseudomode model which can be used to classically simulate the reduced system dynamics. Here, we consider an alternative point of view and analyze the potential benefits of an analog or digital quantum simulation of the pseudomode model itself. Superficially, such a direct experimental implementation is, in general, impossible due to the unphysical properties of the effective degrees of freedom involved. However, we show that the effects of the unphysical pseudomode model can still be reproduced using measurement results over an ensemble of physical systems involving ancillary harmonic modes and an optional stochastic driving field. This is done by introducing an extrapolation technique whose efficiency is limited by stability against imprecision in the measurement data. We examine how such a simulation would allow us to (i) perform accurate quantum simulation of the effects of complex non-perturbative and non-Markovian environments in regimes that are challenging for classical simulation, (ii) conversely, mitigate potential unwanted non-Markovian noise present in quantum devices, and (iii) restructure some of some of the properties of a given physical bath, such as its temperature.