Superconducting nanowire single-photon detectors with 98% system detection efficiency at 1550  nm

Abstract

Superconducting nanowire single-photon detectors (SNSPDs) are an enabling technology for myriad quantum-optics experiments that require high-efficiency detection, large count rates, and precise timing resolution. The system detection efficiencies (SDEs) for fiber-coupled SNSPDs have fallen short of theoretical predictions of near unity by at least 7%, with the discrepancy being attributed to scattering, material absorption, and other SNSPD dynamics. We optimize the design and fabrication of an all-dielectric layered stack and fiber coupling package in order to achieve <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>98.0</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.5</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> SDE, measured for single-mode-fiber guided photons derived from a highly attenuated 1550 nm continuous-wave laser. This enforces a smaller bound on the scattering and absorption losses in such systems and opens the use of SNSPDs for scenarios that demand high-SDE for throughput and fidelity.