Confinement effects in a guided-wave interferometer with millimeter-scale arm separation

TL;DR

This paper investigates how residual confinement affects phase gradients in guided-wave atom interferometers and demonstrates techniques to mitigate this, enabling longer measurement times and larger arm separations.

Contribution

It introduces methods to reduce phase gradients caused by confinement, allowing for extended interferometer measurement times and larger arm separations.

Findings

Achieved interferometer measurement times up to 72 ms.

Demonstrated arm separations up to 0.42 mm with controlled phase.

Extended times to 0.91 s and separations to 1.7 mm with uncontrolled phase.

Abstract

Guided-wave atom interferometers measure interference effects using atoms held in a confining potential. In one common implementation, the confinement is primarily two-dimensional, and the atoms move along the nearly free dimension under the influence of an off-resonant standing wave laser beam. In this configuration, residual confinement along the nominally free axis can introduce a phase gradient to the atoms that limits the arm separation of the interferometer. We experimentally investigate this effect in detail, and show that it can be alleviated by having the atoms undergo a more symmetric motion in the guide. This can be achieved by either using additional laser pulses or by allowing the atoms to freely oscillate in the potential. Using these techniques, we demonstrate interferometer measurement times up to 72 ms and arm separations up to 0.42 mm with a well controlled phase, or times of 0.91 s and separations of 1.7 mm with an uncontrolled phase.