Transmission of information through mesoscopic scattering systems.

The storage and transmission of information is well defined using the notions of entropy, mutual information and channel capacity as formalized by Shannon. These quantities are calculated for a quantum mesoscopic system in terms of scattering parameters. For a one-dimensional system, the mutual information is related to the thermal conductance. This relation allows to show that for an incident signal of power P, the channel capacity C has a universal upper bound given by C ≤ π√(2P/3h) independent of quantum statistics. A general framework is proposed which makes use of a natural underlying symplectic structure, to relate the entropy of a quantum mesoscopic system to the scattering matrix.