Observation of Interference Between Two Bose Condensates

TLDR

Two sodium condensates were produced in a double‑well potential by evaporative cooling, with the wells separated by about 40 µm using magnetic and optical forces. The freely expanding condensates interfered, producing high‑contrast matter‑wave fringes with a ~15 µm period after 40 ms, confirming their coherence and suggesting applications to atom lasers and the atomic Josephson effect.

Abstract

Interference between two freely expanding Bose-Einstein condensates has been observed. Two condensates separated by ∼40 micrometers were created by evaporatively cooling sodium atoms in a double-well potential formed by magnetic and optical forces. High-contrast matter-wave interference fringes with a period of ∼15 micrometers were observed after switching off the potential and letting the condensates expand for 40 milliseconds and overlap. This demonstrates that Bose condensed atoms are “laser-like”; that is, they are coherent and show long-range correlations. These results have direct implications for the atom laser and the Josephson effect for atoms.