Interaction of light with a single atom in the strong focusing regime

TL;DR

This paper explores the interaction between a single atom and focused light, demonstrating significant scattering and proposing a cavity QED approach to enhance quantum networking capabilities.

Contribution

It introduces a theoretical framework for a nearly concentric cavity to achieve strong focusing and enhanced atom-light interactions for quantum networking.

Findings

Significant backscattered light from a single atom in focused mode

Proposal of a nearly concentric cavity for strong atom-light coupling

Potential for scalable quantum network nodes

Abstract

We consider the near-resonant interaction between a single atom and a focused light mode, where a single atom localized at the focus of a lens can scatter a significant fraction of light. Complementary to previous experiments on extinction and phase shift effects of a single atom, we report here on the measurement of coherently backscattered light. The strength of the observed effect suggests combining strong focusing with the well-established methods of cavity QED. We consider theoretically a nearly concentric cavity, which should allow for a strongly focused optical mode. Simple estimates show that in a such case one can expect a significant single photon Rabi frequency. This opens new perspectives and a possibility to scale up the system consisting of many atom+cavity nodes for quantum networking due to a significant technical simplification of the atom--light interfaces.