Bridging the gap between the Jaynes-Cummings and Rabi models using an intermediate rotating wave approximation

TL;DR

The paper introduces the intermediate rotating wave approximation (IRWA), a new method that smoothly connects the Jaynes-Cummings and Rabi models by separately analyzing co-rotating and counter-rotating terms, applicable across different coupling regimes.

Contribution

The IRWA method provides a unified framework to understand light-matter interactions from strong to ultrastrong coupling, bridging existing models with improved physical insight.

Findings

IRWA agrees with Jaynes-Cummings and Rabi models in their respective regimes

IRWA explains differences between the models across coupling strengths

IRWA accurately captures dynamics in near resonance and large detuning cases

Abstract

We present a novel approach called the intermediate rotating wave approximation (IRWA), which employs a time-averaging method to encapsulate the dynamics of light-matter interaction from strong to ultrastrong coupling regime. In contrast to the ordinary rotating wave approximation, this method addresses the co-rotating and counter-rotating terms separately to trace their physical consequences individually, and thus establishes the continuity between the Jaynes-Cummings model and the quantum Rabi model. We investigate IRWA in near resonance and large detuning cases. Our IRWA not only agrees well with both models in their respective coupling strengths, but also offers a good explanation for their differences.