  We study the quantum-interference effect in the ballistic Aharonov-Bohm (AB)
billiard. The wave-number averaged conductance and the correlation function of
the non-averaged conductance are calculated by use of semiclassical theory.
Chaotic and regular AB billiards have turned out to lead to qualitatively
different semiclassical formulas for the conductance with their behavior
determined only by knowledge regarding the underlying classical scattering.
