Purcell-enhanced dipolar interactions in nanostructures

TL;DR

This paper demonstrates how dielectric environments like slot waveguides can significantly enhance dipolar interactions in thermal atomic vapors, enabling controllable quantum nonlinearities at room temperature for quantum information applications.

Contribution

It introduces a novel integration of thermal vapors with a slot waveguide to enhance atom-light interactions via the Purcell effect, achieving strong, controllable nonlinearities at the few-photon level.

Findings

Atoms in the slot exhibit repulsive interactions enhanced by a factor of 8.

The blueshift of atomic transition frequency vanishes above saturation.

Experimental results agree with Monte-Carlo simulations including dielectric and motional effects.

Abstract

Strong light-induced interactions between atoms are known to cause nonlinearities at a few-photon level which are crucial for applications in quantum information processing. Compared to free space, the scattering and the light-induced dipolar interaction of atoms can be enhanced by a dielectric environment. For this \emph{Purcell effect}, either a cavity or a waveguide can be used. Here, we combine the high densities achievable in thermal atomic vapors with an efficient coupling to a slot waveguide. In contrast to free-space interactions, atoms aligned within the slot exhibit repulsive interactions that are further enhanced by a factor of 8 due to the Purcell effect. The corresponding blueshift of the transition frequency of atoms arranged in the essentially one-dimensional geometry vanishes above the saturation, providing a controllable nonlinearity at the few-photon level. The experimental results are in good agreement with Monte-Carlo simulations that include the dielectric environment, dipolar interactions, and motional effects. The results pave the way towards a robust scalable platform for quantum nonlinear optics and all-optical quantum information processing at room temperature.