Jonathan Greenfield

I am a researcher specializing in superconducting materials and devices, with a primary focus on magnesium diboride (MgB₂). My work with MgB₂ has led to significant advances in understanding its unique superconducting properties, which are crucial for next-generation quantum technologies. For instance, in my published paper, Kinetic Inductance and Non-Linearity of MgB₂ Films, I investigated the kinetic inductance behavior and non-linear response of MgB₂ films. This study not only deepened our fundamental understanding of MgB₂ but also provided the groundwork for engineering high-performance superconducting circuits.

Building on these insights, I am currently developing two innovative applications using MgB₂ technology. First, I am working on a novel phase shifter that leverages the non-linear properties of MgB₂, promising significant improvements in the scalability and performance of microwave circuits for quantum information processing. Second, I am developing MgB₂-based superconducting nanowire single-photon detectors (SNSPDs). These detectors are designed to push the boundaries of photon detection efficiency and timing resolution, which are essential for quantum communication and sensing applications.

In addition to my core work on MgB₂, I also contribute to advancing quantum sensing and imaging systems. I have been involved in the development of the Superconducting Kinetic Inductance Passive Radiometer (SKIPR)—a 150 GHz polarization-sensitive photometric camera optimized for terrestrial imaging. SKIPR employs a focal plane array of 3,840 kinetic inductance detectors (KIDs) and integrates a sophisticated cryogenic system based on a Gifford–McMahon cryocooler paired with a two-stage Adiabatic Demagnetization Refrigerator. The instrument is complemented by a dedicated 1.59 m crossed Dragone telescope on an altitude/azimuth mount, enabling diffraction-limited imaging. Extensive laboratory characterization of the KIDs has confirmed that SKIPR performs with detector noise levels determined solely by the random arrival of ambient photons, achieving a detector yield of 92% across the focal plane.

By bridging fundamental materials science with practical device engineering, my research spans from the microscopic properties of superconductors to the macroscopic realization of quantum-enhanced instrumentation. I am driven by the goal of developing scalable, high-performance quantum devices and sensors that not only advance our scientific understanding but also pave the way for transformative technologies in communication, imaging, and beyond.