Electron pairs without superconductivity

ongoing

My aim with this proposal is to develop an electron pair microscope that can locally detect electron pairs without superconductivity, and to leverage this information to gain unprecedented understanding into quantum materials. The electronic properties of most materials, including metals and insulators, are underpinned by single electrons. Superconductors are a notable exception: here, the charge carriers are electron pairs. It has been proposed, in order to explain quantum materials’ mysterious and potentially useful properties, that electron pairs exist without superconductivity and underpin the properties of materials that are not superconducting. Indeed, tantalizing signatures of electron pairs have been reported in high-temperature and disordered superconductors above their transition temperature Tc. However, experimental evidence of such electron pairing is highly disputed and controversial, because there exists currently no experimental probe to locally distinguish electron pairs without superconductivity from single electrons. With PairNoise, I will develop and build a radically new electron pair microscope – based on a unique proof-of-concept instrument developed in my group – that can unambiguously detect electron pairs with atomic resolution. It combines scanning tunnelling microscopy (STM), microfabrication, and shot-noise spectroscopy. With the electron pair microscope, I will determine the nature of the state above Tc in the most interesting superconductors, conclusively determine whether the pseudogap is due to pairing, and find what limits superconductivity at even higher temperatures in quantum materials. My track record of developing first-of-its-kind STM instruments, and their successful utilization for scientific progress, perfectly positions me to make PairNoise a success and to open up a new research field with further applications in the detection of fractional charges, Majorana modes, and dynamical processes.