  This paper reviews recent studies of mesoscopic fluctuations in transport
through ballistic quantum dots, emphasizing differences between conduction
through open dots and tunneling through nearly isolated dots. Both the open
dots and the tunnel-contacted dots show random, repeatable conductance
fluctuations with universal statistical proper-ties that are accurately
characterized by a variety of theoretical models including random matrix
theory, semiclassical methods and nonlinear sigma model calculations. We apply
these results in open dots to extract the dephasing rate of electrons within
the dot. In the tunneling regime, electron interaction dominates transport
since the tunneling of a single electron onto a small dot may be sufficiently
energetically costly (due to the small capacitance) that conduction is
suppressed altogether. How interactions combine with quantum interference are
best seen in this regime.
