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

TL;DR

This study uses microwave cavities to experimentally investigate universal conductance fluctuations, demonstrating the mathematical equivalence to quantum systems and confirming theoretical predictions with good agreement.

Contribution

It introduces a novel microwave-cavity approach to simulate quantum conductance fluctuations, bridging classical wave chaos with mesoscopic quantum phenomena.

Findings

Good agreement between experimental PDFs and theoretical predictions.

Linear relation observed between dephasing and ohmic loss.

Method effectively removes non-ideal coupling effects.

Abstract

The mathematical equivalence of the time-independent Schrodinger equation and the Helmholtz equation is exploited to provide a novel 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 non-interacting 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 non-ideal coupling between the ports and cavity is removed by a previously developed method based on the measured radiation impedance matrix. The Landauer-Buttiker formalism is applied to obtain the conductance of a corresponding mesoscopic quantum-dot device. We find good agreement for the probability density functions (PDFs) 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.