A laser trap for neutral atoms

A laser trap for neutral atoms, initially potassium (K) is constructed. 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, are studied for trapping neutral K atoms. The confinement of the atoms in the two dimensions perpendicular to the laser will be provided in the cavity of a high power alexandrite laser operating in the doughnut mode tuned slightly to the blue side of the 4s 2S1/2 to 2P3 resonance line of the K atom. This trap concept employs not laser cooling, but rather counterstreaming 4He atoms which are cooled to about 1.5 K, to drastically cool the K atoms to thermal energies well below the trap depth (expected to be about 10 K). K atoms can be lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons (recoil or diffusional heating), if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they recombine with He atoms to form KHe (or KHe2, etc.).