An Exact Solution of a Generalization of the Rabi Model

TL;DR

This paper demonstrates that the Rabi model's solvability stems from it being a limiting case of a more general finite-dimensional system, providing insights into its exact solutions beyond integrability.

Contribution

It reveals the underlying reason for the Rabi model's solvability by linking it to a broader finite-dimensional system through contraction.

Findings

Rabi model is a limiting case of a finite-dimensional system

The solvability is due to this limiting relationship

This approach applies to non-integrable but solvable variations

Abstract

There has been renewed theoretical interest recently in the Rabi model due to Braak's analytical solution and introduction of a new criterion for integrability. We focus not on the integrability of the system but rather why it is solvable in the first place. We show that the Rabi model is the limiting case of a more general finite dimensional system by use of a contraction and suggest that this is the reason for it's solvability, which still applies in the case of non-integrable but solvable variations.