Experimental Realization of an Optical One-Way Barrier for Neutral Atoms

• Published in: arXiv.org 2008-05
• Main Authors: Thorn, Jeremy J, Schoene, Elizabeth A, Li, Tao, Steck, Daniel A
• Format: Article
• Language: English
• Subjects: Cooling; Dipoles; Gaussian beams (optics); Laser beams; Laser cooling; Lasers; Neutral atoms; Optical transition; Potential barriers
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0802.1585

We demonstrate an asymmetric optical potential barrier for ultracold 87 Rb atoms using laser light tuned near the D_2 optical transition. Such a one-way barrier, where atoms impinging on one side are transmitted but reflected from the other, is a realization of Maxwell's demon and has important implications for cooling atoms and molecules not amenable to standard laser-cooling techniques. In our experiment, atoms are confined to a far-detuned dipole trap consisting of a single focused Gaussian beam, which is divided near the focus by the barrier. The one-way barrier consists of two focused laser beams oriented almost normal to the dipole-trap axis. The first beam is tuned to have a red (blue) detuning from the F=1 -> F' (F=2 -> F') hyperfine transitions, and thus presents a barrier only for atoms in the F=2 ground state, while letting F=1 atoms pass. The second beam pumps the atoms to F=2 on the reflecting side of the barrier, thus producing the asymmetry.