Phase-Shift Plateaus in the Sagnac Effect for Matter Waves

TL;DR

This paper investigates the phase behavior in ultracold matter wave Sagnac interferometers, revealing discrete phase jumps called plateaus caused by initial conditions, frame of reference, and interactions, applicable in practical experiments.

Contribution

It demonstrates the existence of phase plateaus in matter wave Sagnac interferometers and introduces a simple dispersion-based interferometry scheme.

Findings

Plateaus persist despite nonlinear interactions.

Plateaus occur under various rotation conditions.

Dispersive ring-trap interferometry is feasible.

Abstract

We simulate ultracold Sagnac atom interferometers using quantum-mechanical matter wavepackets, e.g. Bose-Einstein condensates, that counter-propagate within a rotating ring-trap. We find that the accumulation of the relative phase difference between wavepackets, i.e. the matter wave Sagnac effect, is manifested as discrete phase jumps. These plateaus result from three effects; that the atoms should be initially trapped at rest with respect to the rotating frame, that they counter-propagate with the same group velocities in the rotating frame, and that the imaging is performed in the rotating frame. We show that the plateaus persist in the presence of nonlinear atom-atom interactions, and in atoms undergoing various rotations, and thus will occur during matter wavepacket experiments. We also introduce the simplest possible Sagnac atom interferometry scheme which relies on wavepacket dispersion around a ring-trap.