Condensate fraction in a 2D Bose gas measured across the Mott-insulator transition.
We realize a single-band 2D Bose-Hubbard system with Rb atoms in an optical lattice and measure the condensate fraction as a function of lattice depth, crossing from the superfluid to the Mott-insulating phase. We quantitatively identify the location of the superfluid to normal transition by observing when the condensed fraction vanishes. Our measurement agrees with recent quantum Monte Carlo calculations for a finite-sized 2D system to within experimental uncertainty.
Joint Quantum Institute, National Institute of Standards and Technology, USA. ian.spielman@nist.gov
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Spielman
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Phillips
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Porto