Experimental Test of Universal Conductance Fluctuations by Means of Wave-Chaotic Microwave Cavities

The mathematical equivalence of the time-independent Schrödinger equation and the Helmholtz equation is exploited to provide a means of studying universal conductance fluctuations in ballistic chaotic mesoscopic systems using a two-dimensional microwave cavity. The classically chaotic ray trajectories within a suitably shaped microwave cavity play a role analogous to that of the chaotic dynamics of noninteracting electron transport through a ballistic quantum dot in the absence of thermal fluctuations. The microwave cavity is coupled through two single-mode ports and the effect of nonideal coupling between the ports and cavity is removed by a previously developed method based on the measured radiation impedance matrix. The Landauer-Büttiker formalism is applied to obtain the conductance of a corresponding mesoscopic quantum-dot device. We find good agreement for the probability density functions of the experimentally derived surrogate conductance, as well as its mean and variance, with the theoretical predictions of Brouwer and Beenakker. We also observe a linear relation between the quantum dephasing parameter and the cavity ohmic loss parameter.