Condensed Matter Physics Seminar
2 p.m., Thursday, April 29, 2004
Room 1201, Physics Building
Mott insulator to superfluid transition of ultracold atoms near a Feshbach
resonance
Krishnendu Sengupta
(Physics Department, Yale University)
Abstract: We study ultracold bosonic atoms in an optical lattice
near a Feshbach resonance using an extended Hubbard model. We find that such a
system has three possible ground states: a) Mott insulator b) molecular
condensate (MC) and c)atomic and molecular condenstate (AC+MC). The transiiton
between these phases can be induced by varying the depth of the optical lattice
potential and/or by changing the magnetic field which determines the proximity
of the system to the resonance. We obtain the phase diagram as a function of
these parameters within mean-field theory. We find that the superfluid-Mott
insulator transition may become first order in certain regions of the phase
diagram. We also show that the Mott phases with even or odd total number of
atoms and molecules per site behave differently as we approach the superfluid-insulator
transition point. In particular, the even Mott phases exhibit a reentrant
behavior (MC-insulator-AC+MC) as we vary the magnetic field through the
transition at a fixed optical lattice depth and total density. We also
discuss the experimental implications of our results.
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Host: Yakovenko
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