THE EFFECT OF MODE-COUPLING ON CONDUCTANCE FLUCTUATIONS IN BALLISTIC QUANTUM DOTS

We study the effect of mode coupling on the magnetoconductance fluctua tions of a square ballistic quantum dot fabricated in AlGaAs/GaAs hete rostructure material and defined by Schottky gates. Structures prepare d allow for the independent variation of the number of propagating inp ut and output modes and their coupling to the main cavity. While adjus ting the opening of the input and output point contacts changes the nu mber of modes allowed to propagate into the dot, the excitation from a quantum wire creates an additional selection rule. The autocorrelatio n and Fourier analyses of the fluctuations demonstrate that the format ion of the quantum wire has a strong effect, not only on the average c onductance of the dot but also on the excitation of the semiclassical orbits within it.