Optical billiard tables for atoms
DOI: 10.1063/1.4796329
A quickly moving spot of laser light can appear to draw a continuous circle on a screen. Similarly, a rapidly scanned, tightly focused laser will generate a closed two-dimensional boundary—actually an optical dipole potential boundary that repels closely approaching atoms like the cushions of a billiard table. Ultracold atoms can be confined in the third dimension with an orthogonal standing wave, making the system planar. Research groups at the University of Texas at Austin and at the Weizmann Institute of Science in Israel have now independently created and studied such systems. Two differences from regular billiards are that the atoms penetrate some distance into the walls before rebounding, and the walls are easily moved or redrawn in real time. The groups probed atomic trajectories indirectly by creating a little hole in the optical billiard and measuring the atoms’ escape rate for various billiard geometries, and found excellent agreement with classical chaos theory. In future studies, both teams plan to use optical billiards to test such things as quantum chaos and the effects of noise on the trajectories of atoms. (V. Milner et al., Phys. Rev. Lett. 86 , 1514, 2001. N. Friedman
