Superfluid current disruption in a chain of weakly coupled Bose–Einstein condensates

Abstract

We report the experimental observation of the disruption of the\nsuperfluid atomic current flowing through an array of weakly linked Bose–\nEinstein condensates. The condensates are trapped in an optical lattice\nsuperimposed on a harmonic magnetic potential. The dynamical response of the\nsystem to a change of the magnetic potential minimum along the optical lattice\naxis goes from a coherent oscillation (superfluid regime) to a localization of the\ncondensates in the harmonic trap (‘classical’ insulator regime). The localization\noccurs when the initial displacement is larger than a critical value or, equivalently,\nwhen the velocity of the wavepacket’s centre of mass is larger than a critical\nvelocity dependent on the rate of tunnelling between adjacent sites.