Scanning Josephson Microwave Spectroscopy as a Probe of Impurity States in Superconducting Systems
Abstract
Title: Scanning Josephson Microwave Spectroscopy as a Probe of Impurity States in Superconducting SystemsThis proposal describes a new type of scanned probe method - Scanning Josephson Microwave Spectroscopy - that combines the quantum-defined properties of Josephson junctions with the spatial resolution of scanning tunneling microscopy/spectroscopy (STM/STS) to enable the energy spectrum of a surface to be probed with sub-nm spatial resolution and ~Ghz energyresolution. In contrast to conventional STS, Scanning Josephson Microwave Spectroscopy (SJMS) is fundamentally an optical microscopy method, where microwave photons are locally generated via the AC Josephson effect between a superconducting tip and a superconducting sample. By engineering the shape and impedance of the tip, those photons can be made to couple stronglyto their environment, such that the microwave absorption spectrum of localized features can be probed with sub-nm spatial resolution. This new methodology has two significant advantages over conventional STS. First, because SJMS is an optical spectroscopy method as opposed to an electronic transport method, it is sensitive to energetic features that are not accessible in STS, including electron and nuclear spin resonances, the rotational/vibrational modes of molecules, and excitonic modes in a material. Second, the energy resolution of SJMS is not bound by thermal broadening limits imposed on STS spectra, but rather by the capacitive voltage noise across the junction, which can be engineered to be an order smaller than the thermal broadening limit.These advantages make SJMS immediately useful as a diagnostic tool for superconducting quantum circuitry, and for fundamental research, as a probe of Majorana states and other zerobias features in topological superconductors.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 20, 2020
- Source ID
- N000142012356
Entities
People
- Victor Brar
Organizations
- Office of Naval Research
- United States Navy
- University of Wisconsin System