Novel Trapping Techniques For Shaping Bose-Einstein Condensates

Abstract

A combination of radio frequency radiation and magnetic field gradients was used totrap atoms in dressed states. In a magnetic field with a quadrupole minimum, RFfields resonant with the (|F,mf i) |1,−1i ! |1, 0i transition trapped the atoms onthe surface of a sphere, and gravity caused the atoms to pool at the bottom of thesphere. BECs were transferred into this dressed Zeeman trap with 100% efficiency,with lifetimes of up to 30 s, and trapping frequencies of up to 250 Hz were measured.A hard disk platter with a specially written magnetic pattern was used to generatemagnetic fields to confine atoms tightly. Detrimental interactions with the surfacewere avoided by using an extremely thin film with a large magnetic remnant. BECsof up to 5×104 atoms were produced in cigar shaped traps 40 µm above the surface,and trap frequencies up to 5 kHz were measured. After evaporation, condensed cloudsmoved closer to the surface to probe imperfections in the magnetic potential, revealingdefects at distances closer than 35 µm. Finally, BECs were dropped from a height of350 µm in an attempt to achieve specular reflection, but a large amount of dispersionwas observed.Finally, BECs were loaded into a three-dimensional optical lattice, and a quantumphase transition from a superfluid to a Mott insulator was observed. Using microwavespectroscopy, the density dependent “clock shift” was was found to depend on theoccupation number of the wells. The singly occupied lattice sites were then investigatedas an atomic clock system with no density shift. Linewidths as small as 1 HzFWHM out of 6.8 GHz are comparable to current atomic frequency standards.