Cavity-Modified Collective Rayleigh Scattering of Two Atoms

TL;DR

This paper demonstrates cooperative radiation of two atoms in a cavity, showing interference effects and cavity backaction, with implications for entanglement schemes, supported by classical and quantum models.

Contribution

It provides the first detailed observation of two-atom cooperative scattering in a near-lossless cavity, revealing interference effects and cavity backaction not seen in free space.

Findings

Constructive and destructive interference observed in cavity output.

Cavity backaction reduces the expected power scaling from N^2 to near N.

Enhanced control over atom configurations enables future entanglement applications.

Abstract

We report on the observation of cooperative radiation of exactly two neutral atoms strongly coupled to the single mode field of an optical cavity, which is close to the lossless-cavity limit. Monitoring the cavity output power, we observe constructive and destructive interference of collective Rayleigh scattering for certain relative distances between the two atoms. Because of cavity backaction onto the atoms, the cavity output power for the constructive two-atom case ($N=2$) is almost equal to the single-emitter case ($N=1$), which is in contrast to free-space where one would expect an $N^2$ scaling of the power. These effects are quantitatively explained by a classical model as well as by a quantum mechanical model based on Dicke states. We extract information on the relative phases of the light fields at the atom positions and employ advanced cooling to reduce the jump rate between the constructive and destructive atom configurations. Thereby we improve the control over the system to a level where the implementation of two-atom entanglement schemes involving optical cavities becomes realistic.