We present a predictable single-photon source (SPS) based on a silicon vacancy centre in nanodiamond which is optically excited by a pulsed laser. At an excitation rate of 70 MHz the source delivers a photon flux large enough to be measured by a low optical flux detector (LOFD). The directly measured photon flux constitutes an absolute reference. By changing the repetition rate of the pulsed laser, we are able to change the photon flux of our SPS in a controllable way which in turn can act as a reference. The advantage of our method is that it does not require precise knowledge of the source efficiency, but the source is calibrated by the LOFD and can be used for detector responsivity characterizations at the few-photon level.
An active hyperspectral sensor (AHS) was developed for target detection and classification applications. AHS measures light scattered from a target, illuminated by a broadband near-infrared supercontinuum (SC) light source. Spectral discrimination is based on a voltage-tunable MEMS Fabry-Pérot Interferometer (FPI). The broadband light is filtered by the FPI prior to transmitting, allowing for a high spectral-power density within the eye-safety limits. The approach also allows for a cost-efficient correction of the SC instability, employing a non-dispersive reference detector. A precision of 0.1% and long-term stability better than 0.5% were demonstrated in laboratory tests. The prototype was mounted on a car for field measurements. Several road types and objects were distinguished based on the spectral response of the sensor targeted in front of the car.
The 'Metrology for Industrial Quantum Communication Technologies' project (MIQC) is a metrology framework that fosters development and market take-up of quantum communication technologies and is aimed at achieving maximum impact for the European industry in this area.MIQC is focused on quantum key distribution (QKD) technologies, the most advanced quantum-based technology towards practical application. QKD is a way of sending cryptographic keys with absolute security. It does this by exploiting the ability to encode in a photon's degree of freedom specific quantum states that are noticeably disturbed if an eavesdropper trying to decode it is present in the communication channel. The MIQC project has started the development of independent measurement standards and definitions for the optical components of QKD system, since one of the perceived barriers to QKD market success is the lack of standardization and quality assurance.
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