Collective cavity quantum electrodynamics with multiple atomic levels

TL;DR

This paper investigates how ultracold rubidium atoms with multiple levels interact collectively with a high-finesse optical cavity, revealing how transmission spectra change with varying atom numbers and coupling regimes.

Contribution

It introduces a reduced model to accurately describe the collective spin response of multilevel atoms in cavity QED and demonstrates its agreement with experimental spectra.

Findings

Transmission spectra vary with atom number and coupling strength.

The reduced model accurately predicts spectral changes.

Transition from weak to strong collective coupling regimes.

Abstract

We study the transmission spectra of ultracold rubidium atoms coupled to a high-finesse optical cavity. Under weak probing with pi-polarized light, the linear response of the system is that of a collective spin with multiple levels coupled to a single mode of the cavity. By varying the atom number, we change the collective coupling of the system. We observe the change in transmission spectra when going from a regime where the collective coupling is much smaller than the separation of the atomic levels to a regime where both are of comparable size. The observations are in good agreement with a reduced model we developed for our system.