Measuring the atomic recoil frequency using a perturbative grating-echo atom interferometer

TL;DR

This paper reports progress in precisely measuring atomic recoil frequency using a perturbative grating-echo atom interferometer with three standing-wave pulses, achieving high statistical accuracy and discussing systematic error reduction.

Contribution

It introduces a novel perturbative grating-echo atom interferometer technique for measuring recoil energy with high precision and discusses methods to reduce systematic uncertainties.

Findings

Achieved statistical uncertainty of 37 ppb in measuring recoil frequency.

Demonstrated periodic revival of interference fringes at twice the recoil frequency.

Estimated systematic uncertainty at approximately 6 ppm.

Abstract

We describe progress toward a precise measurement of the recoil energy of an atom measured using a perturbative grating-echo atom interferometer (AI) that involves three standing-wave (sw) pulses. With this technique, a perturbing sw pulse is used to shift the phase of excited momentum states---producing a modulation in the contrast of the interference pattern. The signal exhibits narrow fringes that revive periodically at twice the two-photon recoil frequency, $2\omega_q$, as a function of the onset time of the pulse. Experiments are performed using samples of laser-cooled rubidium atoms with temperatures $\lesssim 5$ $\mu$K in a non-magnetic apparatus. We demonstrate a measurement of $\omega_q$ with a statistical uncertainty of 37 parts per $10^9$ (ppb) on a time scale of $\sim 45$ ms in 14 hours. Further statistical improvements are anticipated by extending this time scale and narrowing the signal fringe width. However, the total systematic uncertainty is estimated to be $\sim 6$ parts per $10^6$ (ppm). We describe methods of reducing these systematic errors.