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The Second Quantum Revolution facilitates the engineering of new classes of sensors, communication technologies, and computers with unprecedented capabilities. Supply chains for quantum technologies are emerging, some focused on commercially available components for enabling technologies and/or quantum-technologies research infrastructures, others with already higher technology-readiness levels, near to the market.In 2018, the European Commission has launched its large-scale and long-term Quantum Flagship research initiative to support and foster the creation and development of a competitive European quantum technologies industry, as well as the consolidation and expansion of leadership and excellence in European quantum technology research. One of the measures to achieve an accelerated development and uptake has been identified by the Quantum Flagship in its Strategic Research Agenda: The promotion of coordinated, dedicated standardisation and certification efforts.Standardisation is indeed of paramount importance to facilitate the growth of new technologies, and the development of efficient and effective supply chains. The harmonisation of technologies, methodologies, and interfaces enables interoperable products, innovation, and competition, all leading to structuring and hence growth of markets. As quantum technologies mature, the time has come to start thinking about further standardisation needs.This article presents insights on standardisation for quantum technologies from the perspective of the CEN-CENELEC Focus Group on Quantum Technologies (FGQT), which was established in June 2020 to coordinate and support the development of standards relevant for European industry and research.

Integrated photonics is an essential technology for optical quantum computing. Universal, phase-stable, reconfigurable multimode interferometers (quantum photonic processors) enable manipulation of photonic quantum states and are one of the main components of photonic quantum computers in various architectures. In this paper, we report the realization of the largest quantum photonic processor to date. The processor enables arbitrary unitary transformations on its 20 input modes with an amplitude fidelity of \\(F_{\\text{Haar}} = 97.4\\%\\) and \\(F_{\\text{Perm}} = 99.5\\%\\) for Haar-random and permutation matrices, respectively, an optical loss of 2.9 dB averaged over all modes, and high-visibility quantum interference with \\(V_{\\text{HOM}}=98\\%\\). The processor is realized in \\(\\mathrm{Si_3N_4}\\) waveguides and is actively cooled by a Peltier element.

Photonic processors are pivotal for both quantum and classical information processing tasks using light. In particular, linear optical quantum information processing requires both largescale and low-loss programmable photonic processors. In this paper, we report the demonstration of the largest universal quantum photonic processor to date: a low-loss, 12-mode fully tunable linear interferometer with all-to-all coupling based on stoichiometric silicon nitride waveguides.

Reconfigurable quantum photonic processors are an essential technology for photonic quantum computing. Although most large-scale reconfigurable quantum photonic processors were demonstrated at the telecommunications C band around 1550 nm, high-performance single photon light sources utilizing quantum dots that are well-suited for photonic quantum computing operate at a variety of wavelengths. Thus, a demand exists for the compatibility of quantum photonic processors with a larger wavelength range. Silicon nitride (SiN) has a high confinement and wide transparency window, enabling compact, low-loss quantum photonic processors at wavelengths outside the C band. Here, we report a SiN universal 12-mode quantum photonic processor with optimal operation at a wavelength of 940 nm, which is compatible with InGaAs quantum dot light sources that emit light in the 900 nm to 970 nm wavelength range. The processor can implement arbitrary unitary transformations on its 12 input modes with a fidelity of 98.6 %, with a mean optical loss of 3.4 dB/mode.

The existence of fully transmissive eigenchannels (\"open channels\") in a random scattering medium is a counterintuitive and unresolved prediction of random matrix theory. The smoking gun of such open channels, namely a bimodal distribution of the transmission efficiencies of the scattering channels, has so far eluded experimental observation. We observe an experimental distribution of transmission efficiencies that obeys the predicted bimodal Dorokhov-Mello-Pereyra-Kumar distribution. Thereby we show the existence of open channels in a linear optical scattering system. The characterization of the scattering system is carried out by a quantum-optical readout method. We find that missing a single channel in the measurement already prevents detection of the open channels, illustrating why their observation has proven so elusive until now. Our work confirms a long-standing prediction of random matrix theory underlying wave transport through disordered systems.

Efficient and reliable measurements of photonic indistinguishability are crucial to solidify claims of a quantum advantage in photonics. Existing indistinguishability witnesses may be vulnerable to implementation loopholes, showing the need for a measurement which depends on as few assumptions as possible. Here, we introduce a semi-device-independent witness of photonic indistinguishability and measure it on an integrated photonic processor, certifying three-photon indistinguishability in a way that is insensitive to implementation errors in our processor.