ERC FUNDED PROJECTS

I propose to use large clouds of cold Ytterbium atoms to observe Anderson localization of light in three dimensions, which has challenged theoreticians and experimentalists for many decades. After the prediction by Anderson of a disorder-induced conductor to insulator transition for electrons, light has been proposed as ideal non interacting waves to explore coherent transport properties in the absence of interactions. The development in experiments and theory over the past several years have shown a route towards the experimental realization of this phase transition. Previous studies on Anderson localization of light using semiconductor powders or dielectric particles have shown that intrinsic material properties, such as absorption or inelastic scattering of light, need to be taken into account in the interpretation of experimental signatures of Anderson localization. Laser-cooled clouds of atoms avoid the problems of samples used so far to study Anderson localization of light. Ab initio theoretical models, available for cold Ytterbium atoms, have shown that the mere high spatial density of the scattering sample is not sufficient to allow for Anderson localization of photons in three dimensions, but that an additional magnetic field or additional disorder on the level shifts can induce a phase transition in three dimensions. The role of disorder in atom-light interactions has important consequences for the next generation of high precision atomic clocks and quantum memories. By connecting the mesoscopic physics approach to quantum optics and cooperative scattering, this project will allow better control of cold atoms as building blocks of future quantum technologies. Time-resolved transport experiments will connect super- and subradiant assisted transmission with the extended and localized eigenstates of the system. Having pioneered studies on weak localization and cooperative scattering enables me to diagnostic strong localization of light by cold atoms.

2 490 717 €

Start date: 2019-10-01, End date: 2024-09-30

By enabling the conversion of forces into measurable displacements, mechanical oscillators have always played a central role in experimental physics. Recent developments in the PI group demonstrated the possibility to realize ultrasensitive and vectorial force field sensing by using suspended SiC nanowires and optical readout of their transverse vibrations. Astonishing sensitivities were obtained at room and dilution temperatures, at the Atto- Zepto-newton level, for which the electron-electron interaction becomes detectable at 100µm. The goal of the project is to push forward those ultrasensitive nano-optomechanical force sensors, to realize even more challenging explorations of novel fundamental interactions at the quantum-classical interface. We will develop universal advanced sensing protocols to explore the vectorial structure of fundamental optical, electrostatic or magnetic interactions, and investigate Casimir force fields above nanostructured surfaces, in geometries where it was recently predicted to become repulsive. The second research axis is the one of cavity nano-optomechanics: inserting the ultrasensitive nanowire in a high finesse optical microcavity should enhance the light-nanowire interaction up to the point where a single cavity photon can displace the nanowire by more than its zero point quantum fluctuations. We will investigate this so-called ultrastrong optomechanical coupling regime, and further explore novel regimes in cavity optomechanics, where optical non-linearities at the single photon level become accessible. The last part is dedicated to the exploration of hybrid qubit-mechanical systems, in which nanowire vibrations are magnetically coupled to the spin of a single Nitrogen Vacancy defect in diamond. We will focus on the exploration of spin-dependent forces, aiming at mechanically detecting qubit excitations, opening a novel road towards the generation of non-classical states of motion, and mechanically enhanced quantum sensors.

2 067 905 €

Start date: 2019-09-01, End date: 2024-08-31

The key ideas motivating this project are that: 1) precise control of the properties of porous systems can be obtained by exploiting bacteria and their fantastic abilities; 2) conversely, porous media (large surface to volume ratios, complex structures) could be a major part of bacterial synthetic biology, as a scaffold for growing large quantities of microorganisms in controlled bioreactors. The main scientific obstacle to precise control of such processes is the lack of understanding of biophysical mechanisms in complex porous structures, even in the case of single-strain biofilms. The central hypothesis of this project is that a better fundamental understanding of biofilm biomechanics and physical ecology will yield a novel theoretical basis for engineering and control. The first scientific objective is thus to gain insight into how fluid flow, transport phenomena and biofilms interact within connected multiscale heterogeneous structures - a major scientific challenge with wide-ranging implications. To this end, we will combine microfluidic and 3D printed micro-bioreactor experiments; fluorescence and X-ray imaging; high performance computing blending CFD, individual-based models and pore network approaches. The second scientific objective is to create the primary building blocks toward a control theory of bacteria in porous media and innovative designs of microbial bioreactors. Building upon the previous objective, we first aim to extract from the complexity of biological responses the most universal engineering principles applying to such systems. We will then design a novel porous micro-bioreactor to demonstrate how the permeability and solute residence times can be controlled in a dynamic, reversible and stable way - an initial step toward controlling reaction rates. We envision that this will unlock a new generation of biotechnologies and novel bioreactor designs enabling translation from proof-of-concept synthetic microbiology to industrial processes.

1 649 861 €

Start date: 2019-01-01, End date: 2023-12-31

Carbonaceous aerosols (organic and black carbon) remain a major unresolved issue in atmospheric science, especially in urban centers, where they are one of the dominant aerosol constituents and among most toxic to human health. The challenge is twofold: first, our understanding of the sources, sinks and physico-chemical properties of the complex mixture of carbonaceous species is still incomplete; and second, the representation of urban heterogeneities in air quality models is inadequate as they are designed for regional applications. The CARB-City project proposes the development of an innovative modeling framework that will address both issues by combining molecular-level chemical constraints and city-scale modeling to achieve the following objectives: (WP1) to develop and apply new chemical parameterizations, constrained by an explicit chemical model, for carbonaceous aerosol formation from urban precursors, and (WP2) to examine whether urban heterogeneities in sources and mixing can enhance non-linearities in chemistry of carbonaceous compounds and modify their predicted composition. The new modeling framework will then be applied (WP3) to quantify the contribution of traditional and emerging urban aerosol precursor sources to chemistry and toxicity of carbonaceous aerosols; and (WP4) to assess the effectiveness of greener-city strategies in removing aerosol pollutants. This work will enhance fundamental scientific understanding as to how key physico-chemical processes control the lifecycle of carbonaceous aerosols in cities, and will improve the predictability of air quality models in terms of composition and toxicity of urban aerosols, and their sensitivity to changes in energy and land use that cities are currently experiencing. The modeling framework will have the required chemical and spatial resolution for assessing human exposure to urban aerosols. This will allow policy makers to optimize urban emission reductions and sustainable urban development.

1 727 009 €

Start date: 2020-01-01, End date: 2024-12-31