Transmission line based readout for cryogenic systems

Abstract

This thesis presents a series of experiments on different mesoscopic systems: a quantum Hall system, a Josephson junction, and a semiconductor-superconductor three-terminal device. Measuring these different systems allows for the power and versatility of radio frequency (RF) readout to be showcased. None of these experiments utilise deliberate matching structures. Each experiment shows a progression in the sophistication of the methods used to perform RF readout, culminating in a new approach - the transmission line resonator (TLR) method - which shows benefits over low frequency methods and over other current RF approaches. The measurements of the quantum Hall system focuses on transmission measurements of the collective excitations called edge magnetoplasmons (EMPs). The links between EMPs and the quantum Hall effect are discussed in detail. Current models for EMPs and the quantum Hall effect are applied to predict the frequency response of EMPs as a function of magnetic field; the need for a new model is demonstrated. A new phenomenological model which contains no free parameters is produced. A single gated Josephson junction (JJ) is measured in reflection. The reflection data is utilised in order to describe inductive changes that occur in this JJ. An equivalent circuit description which seeks to quantitatively describe these changes is presented. Building on the previous measurements, the semiconductor-superconductor device is measured using the TLR approach. This allows the device to be measured simultaneously in transmission and reflection. This system serves as a test-bed for this measurement approach, demonstrating the utility of this method.