POWRE: Quantum Dot Studies of the Two-Dimensional Superconductor-Insulator Transition

Middlebury College, Middlebury VT

Investigators

Abstract

This project addresses the fabrication and properties study of quantum dot devices formed from GaAs/Al0.3Ga0.7As heterostructure substrates for in-situ deposition of thin film superconductors. Two geometries will be tested, one for capacitive coupling between the superconductor and two-dimensional electron gas/quantum dot, the other for direct coupling through a tunnel barrier. Initial experiments will focus on the role of dissipation in reducing phase fluctuations near the su-perconductor-insulator transition, particularly in films with different length scales of disorder. Traditional superconductivity measurements involve macroscopic probes that average over the properties of an entire sample. Mesoscale structures offer the unique ability to probe materials on length scales at which quantum effects dominate. Coupled superconductor-quantum dot structures will provide a powerful means of both analyzing the superconductor-insulator transition and altering and studying electron transport on mesoscopic length scales. %%% This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The POWRE grant creates an opportunity to initiate a significant research project that is not feasible to develop in its entirety at the PI's home institution, Middlebury College. Access to both state-of-the-art facilities at Harvard and researchers who are experts on mesoscopic physics and superconductivity will make possible the develop-ment and initial testing of devices that will form the basis of future experiments performed at Middlebury. This project will provide support for a pre-tenure leave year. During this time the PI will lay the foundations for a significant research program that will both lead to the advancement of knowledge and constitute the research component of student education. The research is ex-pected to contribute basic materials science knowledge at a fundamental level of special relevance to the behavior of superconducting materials, and to assist with the integration of research and education. The project is co-supported by the Division of Materials Research, and the MPS OMA(Office of Multidisciplinary Activities). ***