Progress on the Scanning Majorana Microscope

Quantum dots have proven to be powerful probes for studying a variety of mesoscopic effects. In general, lithographically-defined surface quantum dots and scanning single-electron-transistor (SET) quantum dot microscopes fulfill different niches, in part due to the inability to bring the scanning SET close enough to the surface to provide strong coupling. We show significant progress on a new type of scanning quantum dot microscope which we call the Scanning Majorana Microscope (SMM). This novel probe is capable of resolving single electons entering a quantum dot situated at the tip's apex; and importantly, we are able to position the quantum dot within tunneling range (~1nm) of the surface of a sample. With the ability to strongly couple surface states to the quantum dot and study how the single-electron signal evolves as a function of coupling strength, this probe represents a new tool to study mesoscopic systems, including candidate Majorana states.