A cold-atom Ramsey clock with a low volume physics package

TL;DR

This paper presents a compact cold-atom Ramsey microwave clock using a small volume physics package with a GMOT and a loop-gap resonator, achieving promising short-term stability for portable frequency standards.

Contribution

It introduces a low-volume, simplified cold-atom clock system with a novel additively manufactured cavity, advancing portable atomic clock technology.

Findings

Achieved a short-term stability of 1.5×10⁻¹¹ τ^(-1/2)

Used a 67 cm³ volume cavity with additive manufacturing

Simplified optical setup with a grating magneto-optical trap

Abstract

We demonstrate a Ramsey-type microwave clock interrogating the 6.835~GHz ground-state transition in cold \textsuperscript{87}Rb atoms loaded from a grating magneto-optical trap (GMOT) enclosed in an additively manufactured loop-gap resonator microwave cavity. A short-term stability of $1.5 \times10^{-11} $~$\tau^{-1/2}$ is demonstrated, in reasonable agreement with predictions from the signal-to-noise ratio of the measured Ramsey fringes. The cavity-grating package has a volume of $\approx$67~cm\textsuperscript{3}, ensuring an inherently compact system while the use of a GMOT drastically simplifies the optical requirements for laser cooled atoms. This work is another step towards the realisation of highly compact portable cold-atom frequency standards.