UNIVERSAL QUANTUM SIGNATURES OF CHAOS IN BALLISTIC TRANSPORT

The conductance of a ballistic quantum dot (having chaotic classical dynamics and being coupled by ballistic point contacts to two electron reservoirs) is computed on the single assumption that its scattering matrix is a member of Dyson's circular ensemble. General formulae are obtained for the mean and variance of transport properties in the orthogonal (beta = 1), unitary (beta = 2), and symplectic (beta = 4) symmetry class. Applications include universal conductance fluctuations, weak localization, sub-Poissonian shot noise, and normal-metal-superconductor junctions. The complete distribution P(g) of the conductance g.is computed for the case that the coupling to the reservoirs occurs via two quantum point contacts with a single transmitted channel. The result P(g) is-proportional-to g-1+beta/2 is qualitatively different in the three symmetry classes.