Single-atom trapping in the evanescent field of an integrated photonic resonator

TL;DR

This paper demonstrates the successful trapping of a single ultracold atom near a silicon-nitride resonator using evanescent fields, enabling strong atom-photon interactions for scalable quantum photonic circuits.

Contribution

It introduces a novel evanescent-field trapping method for single atoms on integrated photonic resonators, achieving efficient loading and strong coupling without continuous cooling.

Findings

Trapped atom at 150-200 nm from chip surface

Achieved single-atom cooperativity > 1

Observed trapping durations up to 1 second

Abstract

Strong atom-photon interactions on scalable photonic platforms hold significant potential for both atomic and photonic quantum information platforms. In particular, trapping of a single atom on a planar photonic integrated resonator at the subwavelength distances required for strong coupling to the guided modes has remained an outstanding challenge. Here we demonstrate efficient trapping of a single ultracold rubidium atom within the evanescent field of an integrated silicon-nitride microring resonator, at distances of 150-200 nm from the chip surface. Efficient, single-stroke loading process is achieved using an evanescent-field mechanism related to Sisyphus cooling, in which a single scattering event dissipates the atom's kinetic energy and transfers it into a near-surface trap. We observe logarithmic scaling of trapping durations spanning from sub-millisecond timescales up to 1 second, without continuous cooling. The trapped atom couples efficiently to the resonator, enabling on-chip photon collection, photon antibunching, and Purcell-enhanced spontaneous emission with single-atom cooperativity exceeding unity. Our results establish the potential of CMOS-compatible chip-based atom-photon interfaces for scalable quantum photonic circuits.