Emission of Spin-correlated Matter-wave Jets from Spinor Bose-Einstein Condensates

TL;DR

This paper reports the observation of spin-correlated matter-wave jets emitted from a ferromagnetic spinor Bose-Einstein condensate of lithium-7 atoms, demonstrating collective coherence and potential entanglement in the emitted atomic pairs.

Contribution

It presents the first experimental observation of spin-correlated matter-wave jets in a ferromagnetic spinor BEC, with detailed analysis of spin-momentum correlations and coherence.

Findings

Directional atomic beams generated from spinor BECs.

High-contrast oscillations in spin-momentum correlations upon spin axis rotation.

Numerical models match experimental results and indicate entanglement after long time-of-flight.

Abstract

We report the observation of matter-wave jet emission in a strongly ferromagnetic spinor Bose-Einstein condensate of $^7$Li atoms. Directional atomic beams with $|{F=1,m_F=1}\rangle$ and $|{F=1,m_F=-1}\rangle$ spin states are generated from $|{F=1,m_F=0}\rangle$ state condensates, or vice versa. This results from collective spin-mixing scattering events, where spontaneously produced pairs of atoms with opposite momentum facilitates additional spin-mixing collisions as they pass through the condensates. The matter-wave jets of different spin states ($|{F=1,m_F=\pm1}\rangle$) can be a macroscopic Einstein-Podolsky-Rosen state with spacelike separation. Its spin-momentum correlations are studied by using the angular correlation function for each spin state. Rotating the spin axis, the inter-spin and intra-spin momentum correlation peaks display a high contrast oscillation, indicating collective coherence of the atomic ensembles. We provide numerical calculations that describe the experimental results at a quantitative level and can identify its entanglement after 100~ms of a long time-of-flight.