Exploring Excitonic Superconductivity

Abstract

Excitons are electron-hole pair bound states. They have a small mass and can thus can Bose-Einstein condense at relatively high temperatures. This makes them a good candidate for exploring properties like superconductivity and superfluidity. They can even be used to demonstrate macroscopic scale quantum effects with potential use in quantum computation. Quantum Capacitance is due to screening of coulomb interactions in presence of a 2D Electron Gas. It can act as a measure of compressibility of 2DEGs. In a way negative quantum capacitance can probe electron-electron interactions, and suggests Coulomb and spatial correlations. Optical and electrical signatures of excitonic superconductivity are investigated in a p-i-n heterostructure with AlAs barriers and InAs quantum dots. Specifically, this is done through measurements of photocapacitance photoluminescence at various frequencies and intensities of light and at different biases. Evidence for a two-state coherent system is found.