Coherent Collisions between Bose-Einstein Condensates

TL;DR

This paper investigates matter wave amplification through colliding Bose-Einstein condensates, demonstrating coherence, interference, and potential for detecting quantum squeezing without single-particle detection.

Contribution

It introduces a non-degenerate parametric amplifier for matter waves and shows how reversing the process can reveal quantum squeezing.

Findings

High contrast interference observed confirming coherence

Reversal of amplification demonstrates controllable quantum processes

Limits on decoherence suggest presence of number squeezing

Abstract

We study the non-degenerate parametric amplifier for matter waves, implemented by colliding two Bose-Einstein condensates. The coherence of the amplified waves is shown by observing high contrast interference with a reference wave and by reversing the amplification process. Since our experiments also place limits on all known sources of decoherence, we infer that relative number squeezing is most likely present between the amplified modes. Finally, we suggest that reversal of the amplification process may be used to detect relative number squeezing without requiring single-particle detection.