Mesoscopic fluctuations of Coulomb drag between quasi-ballistic 1D-wires

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Quasiballistic 1D quantum wires are known to have a conductance of the order of 2e²/h, with small sample-to-sample fluctuations. We present a study of the transconductance G₁2 of two Coulomb-coupled quasiballistic wires, i.e., we consider the Coulomb drag geometry. We show that the fluctuations in G₁2 differ dramatically from those of the diagonal conductance Gᵢi: the fluctuations are large, and can even exceed the mean value, thus implying a possible reversal of the induced drag current. We report extensive numerical simulations elucidating the fluctuations, both for correlated and uncorrelated disorder. We also present analytic arguments, which fully account for the trends observed numerically.