Long Phase Coherence Time and Number Squeezing of two Bose-Einstein Condensates on an Atom Chip

TL;DR

This study demonstrates extended phase coherence and number squeezing in Bose-Einstein condensates on an atom chip, enabling improved interferometry with potential applications in precision measurements.

Contribution

It reports the first observation of phase coherence lasting up to 200 ms and achieves a tenfold increase in coherence time through initial number squeezing.

Findings

Phase coherence persisted up to 200 ms, ten times longer than the phase diffusion limit.

Number squeezing by a factor of 10 was achieved, enhancing coherence.

Demonstrated a Sagnac interferometer geometry with split condensates.

Abstract

We measured the relative phase of two Bose-Einstein condensates confined in an radio frequency induced double well potential on an atom chip. We observed phase coherence between the separated condensates for times up to 200 ms after splitting, a factor of 10 beyond the phase diffusion limit expected for a coherent state in our experimental conditions (20 ms). The enhanced coherence time is attributed to number squeezing of the initial state by a factor of 10. In addition, we demonstrated a rotationally sensitive (Sagnac) geometry for a guided atom interferometer by propagating the split condensates.