A coherent scattering approach to current noise is used to analyze the transition from ballistic mesoscopic to dissipative macroscopic conduction. The intrinsic current noise for an energy-independent scattering matrix is presented and used to derive the noise for a beam splitter and two-terminal device in the finite temperature, finite frequency, and finite dissipation cases within the noninteracting electron approximation. The generalized Nyquist spectral density is recovered not only for the equilibrium (zero-bias) case, but also for the nonequilibrium (finite-bias) case in the heavily dissipative limit.

• Received 18 May 1994

DOI:https://doi.org/10.1103/PhysRevB.50.17411