Density variations with mm-scale periodicity in optical molasses

Patrick Connolly, Timothy Roach

Mara Goff Prentiss, A. Cable

We have demonstrated that a continuous supply of stow atoms can be produced using a strong standing wave laser field collinear with an atomic beam. Using an interaction length of 27 cm, we typically obtained an atomic beam with a density of ~1 × 10−8cm−3, a most probable velocity of 12 m/s, and a width in velocity space of <12 m/s. We used such a cooled atomic beam to load a magnetic molasses trap.1 We found that the motion of atoms in the trap is not always diffusive but can be confined to very narrow channels, which can be curved and can extend over lengths of several millimeters. In addition, the fluorescence due to the trapped atoms was examined using an optical microscope, and we observed that there were strong spatial variations in the fluorescence. The variations had two distinct components: very regular striations due to interference between the trapping light fields and very irregular variations with a characteristic size scale, which was not strongly correlated with that of the interference fringes.

Theodore Hodapp, Christoph Gerz, Christoph Ira Westbrook +3 more

Shengzhe Wang, Qian-Lan Cai, Zhixin Meng +2 more

We report a compact single-cell source of a continuous cold-atom beam with three-dimensional (3D) cooling. By integrating an off-axis moving optical molasses (OM) with a two-dimensional magneto-optical trap (MOT), we achieve simultaneous 3D cooling within a 50 mm interaction region. The source delivers a continuous flux up to 4.9(5)x10^9 atoms/s, with a transverse temperature of 94(5) microK, a longitudinal temperature as low as 231(65) microK, and a tunable mean velocity between 5 and 20 m/s. Custom in-vacuum mirrors integrate the reflective geometry for the off-axis OM beams with a 0.8 mm output aperture, ensuring stable alignment while suppressing stray light and fluorescence leakage. Ultra-low light shift and decoherence are verified via continuous Raman-Ramsey interferometry, yielding a light shift of -0.51(4)Hz and a typical fringe contrast of 90.85(30)% at a Raman separation of 100 mm (interrogation time of 8.70 ms). This compact continuous cold-atom beam source constitutes a practical building block for atomic-beam clocks and interferometers, enabling reduced aliasing noise together with improved sensitivity and accuracy for field applications.

William D. Phillips, Paul D. Lett, S. L. Rolston +7 more

P. L. Gould, Paul D. Lett, William D. Phillips