Sandia Labs FY22 Laboratory Directed Research & Development Annual Report

FY22 ANNUAL REPORT

SINGLE PHOTON DETECTION WITH ON-CHIP NUMBER-RESOLVING CAPABILITY. The ability to detect single photon quanta plays a key role in fundamental science and advanced engineering applications. Rapid development of quantum information applications is now necessitating on-chip single photon detection (SPD) with deterministic number resolution in the microwave range of the EM spectrum. In this project, the Sandia team achieved high quality materials synthesis, and experimentally explored and theoretically simulated microwave response and SPD in superconducting quantum interference devices (SQUID) realized in topological Dirac semimetals (DSM). Importantly, these initial results reveal that DSMs are a promising material system for SPD at the needed microwave frequencies. The studies of the microwave response of DSMs,

years ago. This project produced nine high impact journal publications, five Technical Advances, and one submitted U.S. patent application. (PI: Wei Pan)

conducted in collaboration with the College of William & Mary and Sandia Alliance partner Georgia Tech, led to a high-impact discovery of the presence of the Leggett mode, a collective quantum phenomenon predicted more than 50

One publication, Single-Crystal Synthesis and Characterization of Copper-Intercalated ZrTe 5 , was featured on the cover of Crystal Growth & Design.

The top left shows the as-grown single crystal and a SQUID. The superconducting (SC) proximitized surface (ф) and bulk (ф) channels are coupled via interband pairing (U interband ), giving rise to a Leggettt mode. The suppression of the even Shapiro steps (high dV/dl value) at 9 GHz is due to the Leggettt mode.

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