Conductance fluctuations in the ballistic regime: A probe of quantum chaos?

We demonstrate the existence of resistance fluctuations in experimentally realizable ballistic conductors due to scattering from geometric features. The magnetic-field and energy correlation functions are calculated both semiclassically and exactly numerically, and are found to have a scale determined by the underlying chaotic classical scattering. These systems provide a test of the ``random'' quantum behavior of classically chaotic systems.