FRIDAY, March 13, 2009

Jadwin Hall Room 303, 2:00 PM

Mikio Nakahara Kinki University "Topological Vortex Formation in BEC of Alkali Atoms as Quantum State Engineering"
A quantized vortex in BEC is a manifestation of coherence in a superfluid. Most proposals of vortex formation in BEC of alkali atoms have made use of rotation of the condensate in one way or another, such as stirring by an optical spoon or rotation of the trapping potential. Several years ago, we proposed an alternative scenario, in which no rotation is involved but the vortex phase is imprinted by making use of the Berry phase associated with an adiabatic change of the magnetic field. The BEC is initially confined in the Ioffe-Pritchard trap. Then the axial field is reversed. This results in the formation of a vortex with the winding number 2F at the center, where F is the hyperfine spin of the atom. Our scenario has been experimentally demonstrated at MIT with 23Na atoms and at Kyoto with 87Rb atoms. There is a subtle difference between two results. We show that the difference is attributed to the difference in the atomic masses. *Prof. Nakahara's chief interest is in quantum computing. He is the author of the well-known book " Geometry, Topology and Physics" Folks interested in chatting with him should contact Toni or N. P. Ong(

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