Purified pseudomode model for nonlinear system-bath interactions

TL;DR

This paper extends the purified pseudomode theory to nonlinear system-bath interactions, enabling analysis of complex quantum systems and environments with applications in nanophotonics and quantum biology.

Contribution

The authors develop a generalized purified pseudomode approach for nonlinear interactions, expanding its applicability beyond linear system-bath models.

Findings

Validated the method with a two-level atom in a lossy cavity.

Applied the approach to calculate resonance fluorescence of a quantum dot.

Demonstrated potential for broad applications in quantum technologies.

Abstract

The theory of purified pseudomodes [arXiv:2412.04264 (2024)] was recently developed to provide a numerical tool for the analysis of the properties of a quantum system and the environment it couples to via linear system-bath interactions. Here we extend this theory to allow for the description of general nonlinear system-bath interactions. We demonstrate the validity of our method by considering the spontaneous decay of a two-level atom placed inside a single-mode lossy cavity and furthermore, its potential application to nanophotonics by calculating the resonance fluorescence spectrum of a quantum dot in the presence of a phonon environment. Our method provides a useful tool for the study of phonon-assisted emission in quantum dots and holds the the promise for broad applications in fields like quantum biology, nonlinear phononics, and nanophotonics.