Quantum Light Source for On-Site Detector Calibration

Ongoing Ramp;D into quantum computing, quantum communications, and quantum networking solutions requires optical detectors that can detect a single photon with high efficiency. For many experiments, it is critical to know the precise detection efficiency of these detectors. Calibrating these detectors is currently anbsp;challenge as these detector are often large, complex, and fragile and must be shipped to a calibration facility for measurement. We propose an alternate method of detector calibration that permits on-site detector calibration using a small, rugged quantum bi-photon source. These bi-photon sources can be used with a calibration method previously reported and demonstrated by NIST (the Klyshko method).nbsp;As part of ournbsp;proposed Phase I project, a proof-of-principle demonstration of the Klyshko calibration method will be implemented using a commercial-off-the-shelf (COTS) bi-photon sourcenbsp;offered by Qubitekk. The calibration accuracy achievable with this non-optimized COTS source will be demonstrated and documented. This COTS source design will then serve as the starting point for an optimized, enhanced stability, prototype bi-photon source for on-site detector calibration. The performance improvements of this prototype source design will be estimated through optical modeling and experimental measurements and compared against the COTS source specs and testing data. The suitability of the prototype for various environments (both space-based and terrestrial) will be evaluated through modeling and comparison with prior testing data. The ability of the prototype source to characterize SPD efficiency across a broad wavelength spectrum will be evaluated and any spectral gaps or range limitations identified. The design and anticipated performance improvements related to this prototype, optimized bi-photon source will be detailed in the projectrsquo;s final report and its construction and testing proposed as part of any follow-on Phase II effort.