Strong Interactions of Single Atoms and Photons near a Dielectric Boundary

TL;DR

This paper demonstrates real-time detection and feedback control of single atoms near a micro-toroidal resonator, revealing quantum atom-cavity interactions influenced by Casimir-Polder forces, advancing scalable quantum network development.

Contribution

It introduces a method for localizing and monitoring single atoms within 100 nm of a dielectric surface, enabling exploration of strong atom-photon interactions in complex resonator systems.

Findings

Observation of significant Casimir-Polder effects on atom dynamics

Real-time feedback enables atom localization near resonator surface

Quantum nature of atom-cavity interactions confirmed through spectral measurements

Abstract

Modern research in optical physics has achieved quantum control of strong interactions between a single atom and one photon within the setting of cavity quantum electrodynamics (cQED). However, to move beyond current proof-of-principle experiments involving one or two conventional optical cavities to more complex scalable systems that employ N >> 1 microscopic resonators requires the localization of individual atoms on distance scales < 100 nm from a resonator's surface. In this regime an atom can be strongly coupled to a single intracavity photon while at the same time experiencing significant radiative interactions with the dielectric boundaries of the resonator. Here, we report an initial step into this new regime of cQED by way of real-time detection and high-bandwidth feedback to select and monitor single Cesium atoms localized ~100 nm from the surface of a micro-toroidal optical resonator. We employ strong radiative interactions of atom and cavity field to probe atomic motion through the evanescent field of the resonator. Direct temporal and spectral measurements reveal both the significant role of Casimir-Polder attraction and the manifestly quantum nature of the atom-cavity dynamics. Our work sets the stage for trapping atoms near micro- and nano-scopic optical resonators for applications in quantum information science, including the creation of scalable quantum networks composed of many atom-cavity systems that coherently interact via coherent exchanges of single photons.