Progress toward an alexandrite laser trap for potassium atoms

Kellan Kremer, Matt Butschek, Jonathan Wrubel

Eite Tiesinga, Paul S. Julienne, Xiaotian Wang +3 more

K.-H. Yang, X.-Z. Zeng, W. C. Stwalley

A detailed description of a corner-cube laser trap concept inside the cavity of a cw alexandrite laser operating in the TEM 01 * mode and using 4He cooling (at temperature ≲ 1.5 K) for trapping neutral potassium atoms is given in a recent paper.1 We report recent progress made toward the implementation of this trap concept: in optimization of the design of the laser cavity, in the understanding of the thermal lensing effects in the alexandrite laser, and in the status of the cryogenic apparatus.

William C. Stwalley

The purpose of this project was to theoretically study and design a laser trap for neutral atoms. At low atomic densities, such a trap could be used to address a number of fundamental questions, e.g., the interaction of an individual atom with an electromagnetic field, collision dynamics, recombination. In particular, after examining a variety of laser-magnet trap concepts, we studied the feasibility and limitations of a 'corner cube' laser trap for potassium atoms based on a near-resonant CW TEM sub 01 ('doughnut mode') alexandrite laser beam with cooling provided by He4 atoms at approx. 1.5 K and designed initial experiments.

William C. Stwalley

This project constructed and studied a laser trap for neutral atoms, initially potassium (K). At low densities, such a trap could be used to address a number of fundamental questions, e.g. the interaction of an individual atom with an electromagnetic field, collision dynamics and recombination. The feasibility and limitations of a purely laser trap concept, a corner cube trap , for trapping neutral K atoms are studied. The confinement of the atoms in the two dimensions perpendicular to the laser is provided in the cavity of a newly constructed high power alexandrite laser operating in the (doughnut mode) tuned slightly to the blue side of the resonance line of the K atom. By reflecting the laser back on itself with two mirrors, one caps the ends of the cylindrical trap, resulting in a slightly weaker end plug. Examined are various loss mechanism for the trapped atoms. In particular, K atoms are lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons, if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they recombine with He to form KHe (or KHe2, etc).

Giovanni Carlo Modugno, G. Roati