NOVEL OPTICAL TRAP OF ATOMS WITH A DOUGHNUT BEAM

We have constructed a novel optical trap for neutral atoms by using a Laguerre-Gaussian (doughnut) beam whose frequency is blue detuned to t he atomic transition. Laser-cooled rubidium atoms are trapped in the d ark core of the doughnut beam with the help of two additional laser be ams which limit the atomic motion along the optical axis. About 10(8) atoms are initially loaded into the trap, and the lifetime is 150 ms. Because the atoms are confined at a point in a weak radiation field in the absence of any external field, ideal circumstances are provided f or precision measurements. The trap opens the way to a simple techniqu e for atom manipulation, including Bose-Einstein condensation of gaseo us atoms.