DEMONSTRATION OF A MICROWAVE TRAP FOR CESIUM ATOMS

We report on the first realization of a microwave trap for neutral ato ms, as proposed originally for use with spin-polarized hydrogen [1]. T his trap is advantageous for attaining Bose condensation because it ca n contain strong or weak field seekers, while static magnetic traps co ntain only the less-stable weak-field seeking states. In this experime nt, Cs atoms were confined in the microwave field of a room-temperatur e spherical resonator (Q almost-equal-to 5500) whose TE 110 mode is tu ned to the blue of the ground state hyperfine splitting (9.2 GHz). Usi ng up to 83 W of microwave power, the trap is shallow (less-than-or-eq ual-to 100 muK), large (almost-equal-to 1 cm) and cannot, by itself, h old Cs atoms up against gravity. We levitate atoms in the trapping sta te (F = 4, m(F) = 4 ground state) with a static magnetic field gradien t. The trap is loaded with atoms cooled to 5 muK in optical molasses. To detect the atoms, we either release them from the trap and detect t heir fluorescence as they fall through a probe laser beam, or we obser ve them with a ccd camera as we illuminate them with laser pulses. Pla ns for applying this technique to spin-polarized hydrogen will be disc ussed in a separate presentation [2].