Dispersive regime of the Jaynes-Cummings and Rabi lattice

TL;DR

This paper extends the understanding of the dispersive regime in Jaynes-Cummings and Rabi lattices to many-site systems, revealing complex interactions like photon pairing and squeezing through theoretical analysis and exact diagonalization.

Contribution

It provides a theoretical framework for the dispersive regime in multi-site lattices, including strong and ultra-strong coupling, and explores emergent phenomena such as photon pairing.

Findings

Spatially extended qubit-qubit and photon-photon couplings

Emergence of photon pairing and squeezing

Validation through exact diagonalization of the Rabi dimer

Abstract

Photon-based strongly-correlated lattice models like the Jaynes-Cummings and Rabi lattices differ from their more conventional relatives like the Bose-Hubbard model by the presence of an additional tunable parameter: the frequency detuning between the pseudo-spin degree of freedom and the harmonic mode frequency on each site. Whenever this detuning is large compared to relevant coupling strengths, the system is said to be in the dispersive regime. The physics of this regime is well-understood at the level of a single Jaynes-Cummings or Rabi site. Here, we extend the theoretical description of the dispersive regime to lattices with many sites, for both strong and ultra-strong coupling. We discuss the nature and spatial range of the resulting qubit-qubit and photon-photon coupling, demonstrate the emergence of photon- pairing and squeezing, and illustrate our results by exact diagonalization of the Rabi dimer.