Cells are constantly exposed to mechanical stimuli that provide important signals which, combined with others from the cellular microenvironment, regulate a plethora of functions at molecular, cellular, and tissue levels. A typical example is the cardiac muscle, the failure of which remains a central health and societal issue. Approaches making it possible to address cell mechanobiology on different spatial and temporal scales within an integrated biological system are still lacking, although this would be of tremendous importance to tackle a great number of various biological processes linked to illnesses such as heart ischemia. OPTO-MECHA-3D is an ingenious new technology to conceptualize cell mechanobiological approaches in 3D ex vivo tissue models. In this project, we aim to develop a dedicated multiscale and multifunctional imaging platform capable of dealing with such 3D models, as well as both interacting with and perturbing them mechanically in a spatially resolved and well-defined fashion. A successful demonstration of the potential of our technology with ex vivo cardiac tissue would represent a major milestone for the future of biomedical research, since OPTO-MECHA-3D has the potential of becoming the standard for studying, not just cardiac function, but various cell mechano-physiological processes that are of interest in many biological fields. The central idea of the project is to associate an intelligent sample holder based on hydrogels that will produce the mechanical stimulus into a light sheet fluorescence microscopy (LSFM) setup that will give access to the response of the cardiac tissue to the stimulus For this, OPTO-MECHA-3D will bond 5 academic teams and an industrial partner: ITAV (CNRS laboratory, specialist of light sheet fluorescence microscopy), I2MC (INSERM unit, specialized in cardiovascular diseases), IMRCP (CNRS unit, expertise in hydrogel synthesis and photoresponsive systems), ICFO in Spain (specialist of photonic microscopy) and FHNW in Switzerland (expertise in laser development). The last partner is Kaivogen Inc, a finnish company specialized in up-converting nanoparticles, which will be incorporated in the hydrogels. This consortium enables to join together the different disciplines which are essential for the carrying out of the work, but the ANR funding would enable the consortium to get more optimized (possibly by addition of one or 2 new partners), answering critical comments from two former proposal submissions in 2016 and 2017.

Nanoscale quantum optics is a promising new field aimed at coherent control and manipulation of single photons emitted by individual quantum emitters in a nanostructured photonic environment. Single emitters have dimensions much smaller than the wavelength of light, and therefore interact slowly and omni-directionally with radiation, placing limits on photon absorption and emission. These intrinsic fluorescence limits can be overcome when the source is placed in a nanostructured photonic material. Multi-scale (fractal) structures are a new class of particularly interesting photonic materials, since they lead to spatial localisation of the electromagnetic energy into subwavelength areas (hot spots of 10s of nm) over a wide spectral range, which are driven by optical excitations coupled to the network on different scales. Here I propose to investigate collective plasmonic systems, based on plasmon multiple scattering and interference on metallic networks. I will study natural gold networks and artificially designed one. I will approach these structures using a network theory approach, a statistical method centred on the network topology, made of links and nodes. This method has the potentiality of describing the complex system with few robust parameters, extracted from the rich microscopic details, and thus provides much deeper understanding. The study of network optical properties will focus on probing one of the most robust modal properties: the local density of optical states. This is a key fundamental quantity involved in light-matter interaction, as it provides a direct measure for the probability of spontaneous light emission (the Purcell effect), light absorption and scattering. I propose to identify the emergent nature of the different optical modes of complex plasmonic networks by studying the statistics of the LDOS in artificial plasmonic networks. I plan to understand the inner character of the complex plasmonic modes, and to reveal subwavelength "hot-spots", critically localized states and chaotic mode signatures. This knowledge will be exploited to design and engineer the LDOS for local fluorescence enhancement and to exploit the network as an unconventional antenna to control the fluorescence of an individual colloidal quantum dot, enhance its radiation rate, boost and manipulate its directionality. I will aim at demonstrating a strong link between the plasmonic network structures, their optical properties and their effect on a light emitter.

The theoretical description of matter in strong laser fields is a rather challenging task. This is due to the fact that the external laser field is comparable to the atomic binding forces, and the usual theoretical methods considered in optical physics, such as perturbation theory with the laser field, are not applicable. In particular, it is very difficult to apply analytical or semi-analytical methods to such a physical framework. There exists, however, one such method, namely the Strong-Field Approximation. This method has served to establish the main paradigms in strong-field laser physics, and has been employed in over 500 publications in this field of research. In particular, it is very powerful for studying quantum interference effects in detail. This approximation suffers, however, from severe drawbacks, which are particularly critical for molecules and systems involving more than one electron. Such systems can not be described by such an approximation in a satisfactory way, and indicate that new, radical ideas are necessary in order to develop the theory further. In this project, we intend to bring ideas and methods from quantum-field theory and mathematical physics to strong-field laser physics to develop a new semi-analytical approach which replaces such an approximation. As a testing ground, we will use such a theory to describe molecules in strong laser fields, and, simultaneously, make a rigorous assessment of the limitations of the Strong-Field Approximation. Such systems have been chosen not only due to their critical behavior, but also due to the fact that, nowadays, there exists pioneering experiments in Britain, at the Imperial College, involving molecules, which will pave the way towards dynamic measurements of matter with a never-imagined precision. This will not only be important for the specific physical systems above, but will revolutionalize a whole area of research.

Cavity-mediated cooling has emerged as the only general technique with the potential to cool molecular species down to the microkelvin temperatures needed for quantum coherence and degeneracy. The EuroQUAM CMMC project will link leading theoreticians and experimentalists, including the technique's inventors and experimental pioneers, to develop it into a truly practical technique, reinforcing European leadership in this field. Four major experiments will explore a spectrum of complementary configurations and cavity-mediated cooling will be applied to molecules for the first time; a comprehensive theoretical programme will meanwhile examine the underlying mechanisms and identify the optimal route to practicality. The close connections between theory and experiment, and between pathfinding and underpinning studies, will allow each to guide and inform the others, ensuring that cavity-mediated cooling is swiftly developed as a broad enabling technology for new realms of quantum coherent molecular physics and chemistry.The Southampton component will address, both experimentally and theoretically, fundamental aspects of the cooling process that result from the retarded interaction of a trapped molecule with its reflection in a single mirror, and developments of this prototype scheme that exploit nanostructured mirror arrays that can be produced in our fabrication facilities, and which show both geometric and plasmonic resonances. Our particular aims are hence to understand and explore the most basic version of cavity-mediated cooling, and to develop new implementations suitable for nanoscale integration as a future technology.