Laser cooling and qubit measurements on a forbidden transition in neutral Cs atoms

TL;DR

This paper demonstrates high-fidelity, background-free hyperfine-level measurements of individual Cs atoms using laser cooling and imaging on a forbidden transition, with potential for rapid, repeated quantum state detection.

Contribution

It introduces a novel method for hyperfine-resolved detection in Cs atoms using a forbidden transition, achieving near-perfect fidelity and enabling rapid, repeated measurements.

Findings

Achieved hyperfine-resolved detection with fidelity 0.9993

Demonstrated atom retention of 0.9954 during measurements

Projected fidelity of 0.9995 with extended approach in 60 microseconds

Abstract

We experimentally demonstrate background-free, hyperfine-level-selective measurements of individual Cs atoms by simultaneous cooling to $5.3~\mu\rm K$ and imaging on the $6s_{1/2}\rightarrow 5d_{5/2}$ electric-quadrupole transition. We achieve hyperfine resolved detection with fidelity 0.9993(4) and atom retention of 0.9954(5), limited primarily by vacuum lifetime. Performing state measurements in a 3D cooling configuration enables repeated low loss measurements. A theoretical analysis of an extension of the demonstrated approach based on quenching of the excited state with an auxiliary field, identifies parameters for hyperfine-resolved measurements with a projected fidelity of $\sim 0.9995 $ in $\sim 60~\mu\rm s$.