Single-photon sources and detectors dictionary

Abstract

The intention of this dictionary is to define relevant terms and metrics used in the characterization of single-photon detectors and sources with the goal to promote better understanding and communication of those metrics across the single-photon technology community. With the recent emergence and significant growth of a “quantum-component industry,” the need for common definitions of terms is clear and pressing. For example, a recent workshop sponsored by the Quantum Economic Development Consortium [QC23] identified the need for a common set of definitions for single-photon device performance metrics [QED23]. There are some existing documents relevant to this need, but they are focused on somewhat different purposes or on one specific application. For example, the ETSI document [LL09, ETS18] focuses specifically on the application of quantum key distribution, and there is a vocabulary resource under the auspices of the CIE (International Commission on Illumination). That CIE resource [CIE20] is focused on the illumination industry. For completeness we also mention several publications which contain some compendiums of single photon definitions [EFMP11, MPFB13a, MSSM20]. Our effort here is intended to compliment and build on those existing reference documents, to create a dictionary independent of a particular single-photon application (for long-term relevance) and to promote clarity and understanding when terms and metrics relevant to single-photon sources or detectors are used by the community. This document also seeks to dispel common misconceptions and to make a few subtle distinctions that will benefit the community. This document may form the basis for a future standards document. With that as a goal, we facilitated a thorough peer-review by fellow National Institute of Standards and Technologies colleagues, the Quantum Economic Development Consortium, representatives of other National Metrology Institutes, and the larger single-photon community. We hope that this document will promote a community-wide consensus on the definitions herein and help facilitate the growth of the single photon industry.