Today, information systems are one of the world's main resources. As accentuated by the Covid-19 crisis, our society relies on an ever-increasing need to process and communicate data, with significant repercussions on politics, defense, health, innovation, daily-life and the economy. The level of security remains a major issue for many use-cases, where secret key encryption are provably secure and can be implemented in the real world via quantum solutions. Quantum-safe communication, the first commercially available quantum technology, provides a unique means to establish, between distant locations, random strings of identical secret bits, with a level of security unattainable using conventional approaches. The implementation of actual quantum systems has become crucial, given the strong military, societal and economic impacts. This path, considered as one of the most promising for IT innovation, benefits from largely endowed R&D programs, such as the EU Flagship and other national initiatives (UK, Germany, China, USA, France). With the development of quantum computers and sensors, it becomes of prime necessity to connect them. Consequently, tasks such as distributed quantum computing and sensing will lead to a large-scale quantum Internet. The major obstacle to the adoption of such networks lies in the limited distance (~100 km) over which they can be deployed, due to losses in optical fibers and the curvature of the Earth. In the absence of reliable quantum repeaters, the space segment represents the only potential way to circumvent this limitation. To date, the only real demonstrations have been made in China (Micius satellite), but many projects are underway at the international scale. SoLuQS aims at effectively answering this demand by building industrial "entanglement source" prototypes that meet the constraints of spatialization, without compromising their performance. The key words of our achievements will be compactness and integrability, allowing satellite exploitation for both civil and military domains. These devices will eventually allow the connection of 2 metropolitan quantum networks (Paris and Nice). SoLuQS will therefore follow the promising path of new telecom-compatible laser optical communication systems in free space, and is thus part of the ASTRID AAP's thematic axis 3, "Cryptography - Communication", with a focus on "network security", their "operational implementation" based on "multimodal entanglement", as well as "space solutions". We will develop, at the French scale, the necessary tools for spatialization, in view of establishing a secure space/ground communication link, in order to anticipate future satellite realizations. SoLuQS brings together the best international teams in quantum communication (INPHYNI and LIP6) as well as a major French space industrial group (Thales Alenia Space) which will promote both integration and spatialization of the achievements. The consortium will pursue an active knowledge dissemination strategy. IP and the attraction of industrialists have a directly exploitable economic value, both in terms of patents, market reach, and creation of start-ups. We will ensure the training of staff and students as well as the promotion of partners in both the academic and industrial communities. These activities will be complemented by dissemination actions (international conferences, scientific and general public publications, etc.) in order to maximize the project impact. Taken as a whole, our actions will ensure France to play a leading role on the international level, in terms of disruptive quantum technologies for space quantum communication.

This project aims at designing network of semiconductor nanolasers on silicon-on-insulator waveguide circuitry for neuromorphic computing applications. To design networks with many nano-lasers, the consortium will first play a special attention on designing energy efficient self-pulsating. These lasers will subsequently interconnected via the underlying silicon circuitry for neuromorphic computing applications. In this scheme, integrated Mach-Zehnder modulators will be used in order to allow to reconfigure the networks for different applications of neuromorphic computing.

This project intends to design, fabricate and study advanced III-V semiconductor nanostructures-based devices for the generation of coherent optical frequency combs (OFCs) with controllable transverse patterns dynamics. Our approach consists in an optically-injected vertical-emission Kerr Gires-Tournois Interferometer (KGTI) integrated in a compact free-space cavity. The KGTI shall consist in a (Al)GaAs/InGaAs metasurface-based VCSEL, with controlled light confinement and phase dispersion, to enhance fast nonlinear light-matter interaction. The coupled-cavity system will be designed to reach the bistable regime and achieve coherent light states with properties overcoming current limitations for telecom and imaging applications. This new experimental framework will be complemented by the development and bifurcation analysis of a hybrid time-delayed, partial differential equations 3D theoretical model, that includes both transverse 2D diffraction and on-axis temporal dynamics. The external cavity design will allow to pass from a single transverse mode to a highly transverse degenerate (self-imaging) system. In that latter case, we envision the possibility to generate multiple, spatially independent, OFCs. We expect this project to yield as a final product, a first experimental demonstrator of vertically-emitted 1D and 3D OFCs in a mature planar III-V semiconductor based platform. Our vertical KGTI will allow to produce combs with high coherence, low power consumption, GHz repetition rates, and containing hundreds of lines in the near infrared spectral domain, with, thanks to the planar vertical architecture, potentially 10 × 10 transversally multiplexed and reconfigurable beams.These results will have groundbreaking applications for instance in massively parallel comb generation or for double comb sensing application and it will help to overcome several limitations for telecom applications. On the technological and experimental sides, the technical barriers to be lifted consists in developing a microcavity containing a nonlinear material having a very high value of the Kerr nonlinear coefficient. For this objective we plan on using the almost untapped potential of AlGaAs-based semiconductor materials operated below their band-gap. The nonlinear interaction will benefit from the strong light confinement in the microcavity. The microcavity design shall find a compromise between the width of the frequency comb targeted as well as the value of the optical power one wishes to inject into the KGTI system. Critical power threshold for the formation of Kerr combs can be controlled via the external cavity reflectivity and imaging configuration, and detuning of the optical pumping with respect to the microcavity resonance; the sign of the latter allowing also to explore both anomalous and normal dispersion regimes. On the theoretical side, the modeling of the system we wish to realize necessitates using Delay Algebraic Equations (DAEs). While the latter have a great potential for the modeling of dispersive phenomena in photonic systems, their studies is comparatively less developed than those of partial differential equations (PDEs). In addition, if DAEs are the natural choice for studying temporal dispersive dynamics, the diffractive propagation of light in the transverse plane of the cavity as well as field curvature effects induced by lenses and mirrors require using PDEs. As such, a full 3D model shall consists of a hybrid DAE-PDE system whose analysis is way beyond the state of the art and represents an exciting and challenging endeavor. The theoretical aspects of KOGIT will also significantly advance the study of spatio-temporal phenomena in nonlinear media. The proposed experimental framework will be complemented by the development of bifurcation analysis method of a hybrid DAE-PDE system that will constitute a qualitative jump in the state of the art.

Coherent light sources from visible to near-infrared wavelengths have driven innovative developments, impacting various domains (telecommunications, biology, medicine). Significant efforts are currently devoted to further span the near-to-mid-IR spectral region due to tremendous scientific and technological potential application. In this context, octave spanning sources in the mid-IR are essential tools for applications in spectroscopy, materials processing, environmental monitoring, as well as chemical, and bio-molecular sensing. More specifically, developing novel mid-IR fiber-based coherent sources supporting µJ and sub-picosecond pulses, is of utmost importance. The implementation of such mid-IR coherent sources relies on specialty fibers, such as rare-earth doped or highly nonlinear photonic crystal fibers. They are considered as key components for high-power, high-stability, ultra-compact, and reliable laser architectures. The specifications of those fibers, namely the spectral range, brightness, expectable pulse duration, as well as wavelength-agility, can fully be tailored thanks to a refined control of their opto-geometrical properties. Conversely, slightly transversal and/or longitudinal fluctuations can induce detrimental performance through unwanted opto-geometrical parameters alteration, notably the propagation constant and associated derivative. The chromatic dispersion, which is proportional to the second-order derivative of the propagation constant, governs the phase-matching conditions of the non-linear optical processes at the heart of the coherent light sources development. Thus, a refined drawing process over the opto-geometrical parameters of the fiber is mandatory to guarantee the expected performances of those sources. The global strategy for elaborating such advanced optical fibers relies on both a linear progression (fabrication, characterization, and applications) and a cyclic and continuous feedback within this triptych. Most of time, this methodology requires several drawing steps during the process fabrication because the characterization of the samples does not provide an accurate enough and a fast feedback, leading to a fiber with rough opto-geometrical parameters. METROPOLIS aims at exploiting the advantages of quantum optical metrology over classical methods for assessing and refining specialty fiber properties with unprecedented accuracy and reliability. The development of a quantum-based plug-and-play chromatic dispersion measurement benchtop stands as the cornerstone of the project. It will serve as a key enabling tool all along the project for fiber qualification, with direct and efficient feedback to the design and manufacturing process flow. Notably, the flexibility of the setup will permit to measure CD with unprecedented accuracy over short samples, making it possible to both calibrate, improve, and master the fabrication process. This will enable designing speciality fibers dedicated to novel applications in spectroscopy and to a new generation of laser systems in the mid-IR range. More specifically, we aim at producing: - a high repetiton rate (~1 kHz) fibred laser source of ultra-short (<500 fs), intense (~ 1 TW) pulses at 2000 nm based on degenerate four-wave mixing. Such a source opens wide scientific perspectives in light-matter interaction and will be exploited in the framework of this project to seed long wavelength parametric amplifiers. - a down-conversion based mid-IR frequency comb by fourth-order modulation instability. Such frequency combs will exhibit a broad spectral coverage associated with high spectral resolution, addressing gas spectroscopy and sensing. METROPOLIS will not only revolutionize the methodology for elaborating any modern photonic components by exploiting novel quantum optical characterization techniques, but also will substantially impact the development of quantum technologies in our society.

The present project aims at understanding the physics of the most important network on earth for living animals: the hydraulic network conducting sap towards the leaves, which results in efficient photosynthesis and oxygen production released in the atmosphere. Here we propose to explore the rupture of this hydraulic network after cavitation periods, during strong hydric stress, which are expected to occur in a context of global climate change with more severe drought. The objective of this ambitious project gathering physicists and biologists is to obtain a physical understanding of the cavitation propagation at the scale of the conduits within plants. Cavitation is a gaseous embolism that tends to spread, stopping sap circulation. But the exact mechanism and dynamics of the propagation of embolism is still not clear. Three phases will be conducted in parallel to pursue this objective: First, we start with a detailed observation of embolisms in real leaves and wood at very high frequency, in optics with a high-speed camera operating at several thousand images per second or under fast X-rays. Acoustic recordings in the MHz range will also give precious insight. These unprecedented observations may unravel the still unknown reasons for the abrupt and intermittent propagation of embolisms. Attention will be given to the difference between tree species. Second, we will reconstruct basic hydraulic networks in elastomer, in order to be able to model the speed of the propagation of the embolism. We will employ microfluidic techniques to craft the networks. As a starting approximation, constrictions in the channels will mimic the pits connecting conduits together. A more precise approximation will be to include membranes with small pores, which will be closer to the real pits. We will also develop biomimetic channels with an integrated flow regulation, in the objective of modelling stomata that regulate evaporation rates on real leaves. Third, we will address a model of channels closer to real systems, with water under negative pressure inside stiff microchannels made of hydrogel. The propagation of cavitation from channel to channel will be tested when channels are isolated cells. Then we will go towards more realistic microfluidic network, with sap flowing and more complex topologies. These three experimental approaches will be complemented by a modelling effort to tackle the role of physical and chemical parameters from the conduit scale to the xylem network on the embolism spreading dynamics. The main scientific outcome of the project will be a detailed understanding of the resistance of trees to drought. This may prove useful for agricultural purposes, and to the modelling of effect of climate change on trees. New biomimetic autonomous devices regulating humidity, or designed for evaporative microfluidics systems, will also be inspired by this project.