Development and Spectrum Analysis of the Scanning Majorana Microscope

Majorana bound states are difficult to distinguish from trivial near-zero energy states. Single-electron transistor measurements have been proposed as on-chip probes to solve this problem. Combining these devices with scanning probe methods allows us to extend the reach of these probes to test many of the candidate systems that may support Majorana bound states. In this talk, we present progress on the development and testing of the Scanning Majorana Microscope (SMM). This instrument employs a capacitance-based device constructed from a high-electron-mobility transistor, which can measure the single-electron spectra of electrons tunneling into a quantum dot. The device is integrated into a probe tip which is fabricated by thermally evaporating two Al leads (one tunneling lead and one capacitance lead) onto a glass fiber with a quantum dot at the apex. For this talk, we will focus on key milestones that have been accomplished. The first is a demonstration that the probe can adequately perform the basic functions of a scanning tunneling microscopy tip; that is, approaching to within tunneling distance of a conducting surface, and measuring the topography of the surface. The second milestone is the demonstration of the probe’s capability to resolve single-electron tunneling into the quantum dot. For this part we will present a Fourier analysis of a series of capacitance spectra.