UNIVERSAL CONDUCTANCE DISTRIBUTION IN THE QUANTUM-SIZE REGIME

We study the conductance (g) distribution function of an ensemble of i solated conducting rings, with an Aharonov-Bohm flux. This is done in the discrete spectrum limit, i.e. when the inelastic rate, frequency a nd temperature are all smaller than the mean level spacing. Over a wid e range of g the distribution function exhibits universal behaviour P( g) similar to g(-(4+beta)/3) where beta = 1 (2) for systems with (with out) a time reversal symmetry. The non-universal large-g tail of this distribution determines the values of high moments.