Matter-wave recombiners for trapped Bose-Einstein condensates

TL;DR

This paper compares two methods for recombining Bose-Einstein condensates in interferometry, demonstrating their effectiveness in phase measurement and advancing quantum manipulation techniques.

Contribution

It introduces and experimentally compares two novel matter-wave recombination techniques for trapped BEC interferometers.

Findings

Achieved interferometric contrasts of 20% and 42% with the two methods.

Demonstrated successful implementation of both recombination schemes.

Progressed towards coherent manipulation of BEC superposition states.

Abstract

Interferometry with trapped atomic Bose-Einstein condensates (BECs) requires the development of techniques to recombine the two paths of the interferometer and map the accumulated phase difference to a measurable atom number difference. We have implemented and compared two recombining procedures in a double-well based BEC interferometer. The first procedure utilizes the bosonic Josephson effect and controlled tunneling of atoms through the potential barrier, similar to laser light in an optical fibre coupler. The second one relies on the interference of the reflected and transmitted parts of the BEC wavefunction when impinging on the potential barrier, analogous to light impinging on a half-silvered mirror. Both schemes were implemented successfully, yielding an interferometric contrast of about 20% and 42% respectively. Building efficient matter wave recombiners represents an important step towards the coherent manipulation of external quantum superposition states of BECs.