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Time-averaged potentials

We have developed a new apparatus that produces 87Rb Bose-Einstein condensates of 1× 106 atoms. We then transfer the condensate onto a "light sheet" potential using 1064 nm light, which traps the atoms onto a plane. Using another a rapidly scanned laser beam (1064 nm) in the vertical direction, we can "paint" a variety of traps for the atoms. The beam is scanned using a 2D acousto-optical deflector (2D-AOD), and is scanned very a high rate (>5 KHz) so the atoms "see" the time-averaged potential. Using a feedback technique, which uses the distribution of atoms as a probe, we can compensate for intensity variations, and make ultra-smooth homogeneous potentials.

BEC in various time-averaged traps including coupled "dumbell" reservoirs, and lattices with 3, 4 and 6 wells. Each image is 200 µm and 200 µm.

We are particularly interested in

- Superfluid dynamics in ring potentials.

- Sound wave (phonon) excitations in time-averaged potentials.

- Waveguides for BEC interferometry.

- Superfluid convection and heat transport in coupled reservoirs.

BEC of ~ 150,000 atoms in a ring trap, of 140 µm diameter.

BEC of 150,000 atoms released into a 300 µm diameter waveguide, over 100 ms. Each frame is separated by 2.5 ms.