Superconductor-like effects in an AC driven normal Mott-insulating quantum dot array

We study the current response of an AC driven dissipative Mott insulator system, a normal quantum dot array, using an analytical Keldysh field theory approach. Deep in the Mott insulator regime, the nonequilibrium steady state (NESS) response resembles a resistively shunted Josephson array, with a nonequilibrium Mott insulating to conductor transition as the drive frequency Ω is increased. The diamagnetic component of the NESS in the conducting phase is anomalous, implying negative inductance, strikingly reminiscent of the η-pairing phase of a Josephson array with negative phase stiffness. However in the presence of an additional DC field the signature of supercurrent - Shapiro steps - is completely absent. We interpret these properties as number-phase fluctuation effects shared with Josephson systems rather than superconductivity.

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