Atom interferometric techniques for measuring uniform magnetic field gradients and gravitational acceleration

TL;DR

This paper explores advanced atom interferometry techniques to measure magnetic field gradients and gravitational acceleration with high precision, demonstrating long coherence times and improved theoretical models for accurate sensing.

Contribution

It introduces optimized configurations of grating echo atom interferometers with extended signal lifetimes and provides an improved theoretical framework for precise magnetic gradient and gravity measurements.

Findings

Achieved interferometer signal lifetimes of ~270 ms.

Detected magnetic field gradient changes as small as 4×10^{-5} G/cm.

Measured magnetic field gradients with an accuracy of 3×10^{-4} G/cm.

Abstract

We discuss techniques for probing the effects of a constant force acting on cold atoms using two configurations of a grating echo-type atom interferometer. Laser-cooled samples of $^{85}$Rb with temperatures as low as 2.4 $\mu$K have been achieved in a new experimental apparatus with a well-controlled magnetic environment. We demonstrate interferometer signal lifetimes approaching the transit time limit in this system ($\sim 270$ ms), which is comparable to the timescale achieved by Raman interferometers. Using these long timescales, we experimentally investigate the influence of a homogeneous magnetic field gradient using two- and three-pulse interferometers, which enable us to sense changes in externally applied magnetic field gradients as small as $\sim 4 \times 10^{-5}$ G/cm. We also provide an improved theoretical description of signals generated by both interferometer configurations that accurately models experimental results. With this theory, absolute measurements of $B$-gradients at the level of $3 \times 10^{-4}$ G/cm are achieved. Finally, we contrast the suitability of the two- and three-pulse interferometers for precision measurements of the gravitational acceleration, $g$.