BROWNIAN-MOTION MODEL OF PARAMETRIC CORRELATIONS IN BALLISTIC CAVITIES

A Brownian-motion model is proposed to study parametric correlations i n the transmission eigenvalues of open ballistic cavities. For systems with unitary symmetry, we find interesting universal properties when the eigenvalues are rescaled at the hard edge of the spectrum. For sys tems with orthogonal, unitary, and symplectic symmetries a formula for the power spectrum of the fluctuations of transport observables as a response to an external adiabatic perturbation is derived. Our formula correctly recovers the Lorentzian-squared behavior obtained, for unit ary systems, from semiclassical approaches for the correlation functio n of conductance fluctuations.