Superfluid and dissipative dynamics of a Bose-Einstein condensate in a periodic optical potential.
We create Bose-Einstein condensates of 87Rb in a static magnetic trap with a superimposed blue-detuned 1D optical lattice. By displacing the magnetic trap center we are able to control the condensate evolution. We observe a change in the frequency of the center-of-mass oscillation in the harmonic trapping potential, in analogy with an increase in effective mass. For fluid velocities greater than a local speed of sound, we observe the onset of dissipative processes up to full removal of the superfluid component. A parallel simulation study visualizes the dynamics of the Bose-Einstein condensate and accounts for the main features of the observed behavior.
Burger
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INFM-LENS, Dipartimento di Fisica, Università di Firenze, Largo Enrico Fermi 2, I-50125 Firenze, Italia.
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