Flow equation renormalization of a spin-boson model with a structured bath

TL;DR

This paper applies flow equation renormalization to a spin-boson model with a structured bath, enabling analysis of the system's dynamics and correlation functions by decoupling the quantum system from its environment.

Contribution

It introduces a novel application of flow equations to a structured bath spin-boson model, providing a new method for analyzing such systems.

Findings

Successful diagonalization of the model using flow equations

Calculation of spin-spin correlation functions in the structured bath context

Demonstration of decoupling the quantum system from its environment

Abstract

We discuss the dynamics of a spin coupled to a damped harmonic oscillator. This system can be mapped to a spin-boson model with a structured bath, i.e. the spectral function of the bath has a resonance peak. We diagonalize the model by means of infinitesimal unitary transformations (flow equations), thereby decoupling the small quantum system from its environment, and calculate spin-spin correlation functions.