Sandia National Labs FY20 LDRD Annual Report

FY20 ANNUAL REPORT

Single photon detection with on-chip, number-resolving capability. A novel single photon detector (SPD) that operates at microwave frequencies with the potential for deterministic photon number resolving capability is a new development at Sandia. Photon number resolving detectors are highly desired due to their potential to enable major advances in applications including quantum communications and quantum sensing. Existing SPDs do not provide this photon number resolving capability at microwave frequencies due to the low energy of each individual photon. To overcome this challenge, the LDRD team employed topological quantum materials for which the zero-gap superconducting surface states allow for deterministic, number-resolving microwave photon detection. They developed a detailed theoretical model based on their microwave absorption experiments and showed that their approach can lead to a new method for microwave

single photon detection suitable for quantum information science applications. The project has further fostered fruitful collaborations with Georgia Tech and the College of William & Mary. (PI: Wei Pan) Single photon detection in topological quantum materials. The inset depicts a Josephson junction based on Cd 3 As 2 , a topological quantum material. The main plot shows the bulk resistance gain (in microohms) due to absorption of a single photon vs. baseline temperature for photon frequencies f = 5; 10 GHz.

Sandia’s high-performance computer facility received DOE’s Sustainability Award in 2020. (Photo by Bret Latter)

62

LABORATORY DIRECTED RESEARCH & DEVELOPMENT