Mechanism behind non-Mollow resonant fluorescence in a two-component BEC in a cavity

Determine the physical mechanism that causes the resonant fluorescence spectra of a trapped two-component Bose–Einstein condensate with internal states g and e, coupled to two quantized optical modes (cavity and fluorescent) in an optical cavity and driven at the atomic resonance frequency, to deviate from the standard Mollow triplet and instead exhibit multiple peaks that merge into an approximate plateau near the resonant frequency under the studied low-photon conditions.

Background

In the two-component BEC regime the authors drive the system at resonance (ω0 = ΩR) with an initial coherent cavity field and observe that the resulting resonant fluorescence spectra do not display the standard Mollow triplet. Instead, multiple peaks appear, some very broad, merging into an approximate plateau around ω ≈ ΩR.

They note they lack a detailed explanation for this deviation. They suggest that low-photon multiphoton effects and the quantum nature of the coupling (where different (gi, η) pairs can yield the same semiclassical effective coupling but different spectra) as well as many-particle resonant channels due to photon dressing may contribute, but a definitive mechanism is not established.