Over the last few years, the National Research Council of Canada (NRC) has been establishing new facilities and improving capabilities in three areas of radiometry: optical power, spectral irradiance, and few-photon measurements. Canada’s realization of the optical radiant power scale now utilizes a new cryogenic electrical substitution radiometer as the primary instrument. With higher cavity absorptance, reduced non-equivalence effects, and a closed-cycle helium cryocooler, this new cryogenic radiometer has significantly contributed to improvements in measurement uncertainties. NRC’s primary spectral irradiance scale has transitioned from a detector based approach to a detector and source based realization. Filter radiometers with spectral responsivity traceable to the cryogenic radiometer and a high temperature blackbody primary light source are implemented in the calibration of transfer standard FEL lamps from 200 nm to 2500 nm. Most recently, NRC has been working to establish a few-photon metrology capability for optical radiometry. The initial goal of this new facility is to measure the detection efficiency of free-space single-photon detectors using a calibrated detector substitution technique. This capability will then be extended to the traceable characterization of NRC on-chip semiconductor quantum dot-based single-photon sources, the evaluation of these sources as new quantum standards, and using entangled photons from these sources for fundamental quantum metrology measurements. Ongoing efforts and details of these new radiometry facilities will be presented.
Over the last few years, the National Research Council of Canada (NRC) has been establishing new facilities and improving capabilities in three areas of radiometry: optical power, spectral irradiance, and few-photon measurements. Canada’s realization of the optical radiant power scale now utilizes a new cryogenic electrical substitution radiometer as the primary instrument. With higher cavity absorptance, reduced non-equivalence effects, and a closed-cycle helium cryocooler, this new cryogenic radiometer has significantly contributed to improvements in measurement uncertainties. NRC’s primary spectral irradiance scale has transitioned from a detector based approach to a detector and source based realization. Filter radiometers with spectral responsivity traceable to the cryogenic radiometer and a high temperature blackbody primary light source are implemented in the calibration of transfer standard FEL lamps from 200 nm to 2500 nm. Most recently, NRC has been working to establish a few-photon metrology capability for optical radiometry. The initial goal of this new facility is to measure the detection efficiency of free-space single-photon detectors using a calibrated detector substitution technique. This capability will then be extended to the traceable characterization of NRC on-chip semiconductor quantum dot-based single-photon sources, the evaluation of these sources as new quantum standards, and using entangled photons from these sources for fundamental quantum metrology measurements. Ongoing efforts and details of these new radiometry facilities will be presented.
A system for calibrating single photon detector efficiency that is traceable to the SI through a state-of-the-art classical optical fibre radiometer has been developed and is in the process of being vetted as a calibration service at the National Institute of Standards and Technology (NIST). The method of calibration is direct substitution to power meters relative to NIST's optical fibre cryogenic primary standard and builds on the existing measurement infrastructure for the calibration of optical fibre power meters. Recent improvements to the optical fibre cryogenic radiometer make it more robust and deployable. The traceability of the single photon detector calibration service under development to these classical measurements is discussed, along with a description of the technique used in this calibration service to calibrate the detection efficiency of single photon detectors. Finally, we discuss work on the development of these technologies so that in the future they may be deployable to the point-of- use.
Abstract A study of optical fibre power metre calibrations is presented based on comparison with fibre-coupled cryogenic radiometry. Three nearly identical cryogenic radiometers are used together with a free-space absolute spectral responsivity measurement facility. The results show that the dominant sources of uncertainty originate not from the radiometers or the transfer standard detector, but from the optical path components used to convey light from the source to the detector. The properties of the optical radiation, defined by wavelength, polarization, and modal quality, together with system components such as optical fibres, fibre switches, fibre splitters, polarization controllers, and external influences including temperature and vibration, limit the achievable uncertainty. Measurements are performed at optical power levels near 100 µW, a regime in which the underlying measurement technology has matured over several decades. The absolute uncertainty ranges from approximately 0.0010 A W −1 to 0.0043 A W −1 , depending on the wavelength and components. The results provide a quantitative basis for assessing the limits of uncertainty reduction in fibre-based optical power measurements and are relevant to future uncertainty analyses of fibre-coupled single-photon detector efficiency in quantum communications and quantum technologies in general.
Abstract Single-photon sources have a variety of applications. One of these is quantum radiometry, which is reported on in this paper in the form of an overview, specifically of the current state of the art in the application of deterministic single photon sources to the calibration of single photon detectors. To optimize single-photon sources for this purpose, extensive research is currently carried out at the European National Metrology Institutes (NMIs), in collaboration with partners from universities. Single-photon sources of different types are currently under investigation, including sources based on defect centres in (nano-)diamonds, on molecules and on semiconductor quantum dots. We will present, summarise, and compare the current results obtained at European NMIs for single-photon sources in terms of photon flux, single-photon purity, and spectral power distribution as well as the results of single-photon detector calibrations carried out with this type of light sources.
We will present our current efforts on single photon quantum metrology using high-efficiency superconducting detectors and high-efficiency single-photon sources based on spontaneous parametric downconversion. Optical power measurements based on single photon counting could establish a quantum standard for optical power calibration in the future. At NIST we are pursuing the development of single photon sources and single photon detectors for metrology, quantum and classical applications. As part of these efforts, we are pursuing the establishment of a measurement service for the calibration of single photon detectors. We present how our calibration is tied to the calibration of our transfer standard optical fiber power meters. Using the beamsplitter method, we have implemented a fiber-coupled and free-space measurement system. Also, we have developed testbeds and measurement protocols for the characterization of single photon sources and single photon detectors. We will review several methods, which allow for the characterization of the spatial and spectral degree of freedom in spontaneous parametric downconversion.
We report on the experimental realization of an absolute single-photon source based on a single nitrogen vacancy (NV) center in a nanodiamond at room temperature and on the calculation of its absolute spectral photon flux from experimental data. The single-photon source was calibrated with respect to its photon flux and its spectral photon rate density. The photon flux was measured with a low-noise silicon photodiode traceable to the primary standard for optical flux, taking into account the absolute spectral power distribution using a calibrated spectroradiometer. The optical radiant flux is adjustable from 55 fW, which is almost the lowest detection limit for the silicon photodiode, and 75 fW, which is the saturation power of the NV center. These fluxes correspond to total photon flux rates between 190,000 photons per second and 260,000 photons per second, respectively. The single-photon emission purity is indicated by a g((2))(0) value, which is between 0.10 and 0.23, depending on the excitation power. To our knowledge, this is the first single-photon source absolutely calibrated with respect to its absolute optical radiant flux and spectral power distribution, traceable to the corresponding national standards via an unbroken traceability chain. The prospects for its application, e.g., for the detection efficiency calibration of single-photon detectors as well as for use as a standard photon source in the low photon flux regime, are promising. (C) 2017 Optical Society of America
Quantum photonics technologies have realized great advancements over the past decade. Quantum photonic integrated circuits, devices which incorporate single-photon emitters, detectors and optical components on a single device, are already being implemented in quantum computing and networking hardware. The verification and validation of system performance, including the characterization of single-photon sources and the efficiency of single-photon detectors is an ongoing challenge, especially for integrated devices. One approach to characterizing a single-photon source is to measure the optical power of the emitted photons, which can be applied in turn to the characterization of on-chip components within an integrated quantum photonics platform. This presentation will address the development of metrological devices and measurement techniques, where an ultra-sensitive radiometer chip directly measures the optical power of photons emitted from a quantum dot single-photon source. This measurement technique demonstrates the feasibility of implementing optical power measurements of on-demand single photon sources in the verification and validation of quantum photonics systems.