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Atom Waveguides and Interferometers for confined BECís

Prof David Pritchard

Massachusetts Instituite of Technology, USA

11.00am, Tuesday 24 February 2004, AR103 Seminar Room, Graduate Research Centre

Gaseous Bose-Einstein condensates with several million atoms were loaded into a magnetic trap consisting of microfabricated wires on a silicon wafer. They propagated down a magnetic waveguide for 12 mm. Single-mode propagation was observed for BECís fast enough (~4 cm/sec) to overcome a bump in the guide caused by a branch in the waveguide, and slow enough (<6 cm/sec) so that non-uniformities of the guide did not cause strong transverse excitations. In addition, the condensate fragmented when brought to within 100 microns of the surface in the magnetic waveguide, but not in a colocated optical trap at this location, suggesting that the fragmentation is due to small scale irregularities in the current flow in the nanofabricated wires. Recently we have shown that careful attention to reduction of rf and audio frequency noise leads to observed lifetimes of the BEC of tens of seconds for condensates even at this distance from the surface, in contradiction to earlier results showing shortening of the lifetime this close to the surface. We recently demonstrated an atom interferometer made when an optical trap is deliberately split into a widely separated double well from which the atoms are released to make a stable interference pattern. We discuss the prospects of combining these techniques to make an atom interferometer on a chip, a device whose applications we shall discuss. I am grateful to my colleagues for doing, and to NSF, ONR, and ARO for supporting, this research.

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