Cold-atom clock based on a diffractive optic

TL;DR

This paper presents a compact cold-atom clock using a grating magneto-optical trap that achieves high stability with a small physical footprint, suitable for portable quantum technologies.

Contribution

The authors demonstrate a cold-atom clock based on a gMOT with a simplified optical layout, enabling high stability in a compact form factor.

Findings

Achieved a fractional frequency stability of 2×10⁻¹¹/√τ

Collected 10⁷ Rb atoms in a compact setup

Used Raman-Ramsey sequence for precise frequency measurement

Abstract

Clocks based on cold atoms offer unbeatable accuracy and long-term stability, but their use in portable quantum technologies is hampered by a large physical footprint. Here, we use the compact optical layout of a grating magneto-optical trap (gMOT) for a precise frequency reference. The gMOT collects $10^7$ $^{87}$Rb atoms, which are subsequently cooled to $20\,\mu$K in optical molasses. We optically probe the microwave atomic ground-state splitting using lin$\perp$lin polarised coherent population trapping and a Raman-Ramsey sequence. With ballistic drop distances of only $0.5\,$mm, the measured short-term fractional frequency stability is $2 \times 10 ^{-11} /\sqrt{\tau}$.