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Single-photon Sources and Detectors Dictionary



Joshua Bienfang, Thomas Gerrits, Paulina Kuo, Alan Migdall, Sergey Polyakov, Oliver T. Slattery


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.
NIST Interagency/Internal Report (NISTIR) - 8486
Report Number


single-photon source, single-photon detector, quantum optics, quantum networking, quantum communications, quantum optical metrology


Bienfang, J. , Gerrits, T. , Kuo, P. , Migdall, A. , Polyakov, S. and Slattery, O. (2023), Single-photon Sources and Detectors Dictionary, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed May 28, 2024)


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Created September 7, 2023, Updated September 26, 2023