Polaritons, half-light half-matter mixed states arising from the strong coupling between excitons and photons in semiconductor microcavities, are composite bi-dimensional interacting bosons. They can manifest macroscopic quantum coherence effects at high temperatures (5-300 K) due to their very low mass. In particular, polaritons behave like a quantum fluid with specific properties coming from its intrinsic out of equilibrium nature, determined by the short polariton lifetime (some picoseconds). At the same time, microcavity polaritons, due to the strong non-linear polariton-polariton interactions inherited from their excitonic component, are very promising for the realization of integrated optoelectronic devices operating at the quantum level. In the first part of the talk, I will briefly review the superfluid and Cerenkov regimes in these systems, and I will discuss the formation of quantized vortex and dark solitons in a polariton quantum fluid interacting with a large obstacle. The possibility to generate vortex lattices in a confined geometry will be discussed. Finally, I will show how the non linear polariton-polariton interactions can be exploited to achieve for the first time quantum noise reduction on a light beam transmitted by semiconductor micropillar, relying on a Kerr-like effect. These results show the potential for the generation of non-classical states of light with these nanostructures. In the second part of the talk I will present our recent results on efficient room temperature single photon emitters based on core/shell colloidal semiconductor nanocrystals. In such structures, the competition between radiative and non-radiative recombination channels induces photoluminescence fluctuations between on and off states known as blinking. The shell engineering is a suitable strategy to control recombination paths and has been used to produce almost non-blinking nanocrystals, although accompanied by undesired increasing of multi-excitonic emission probability. By using asymmetric core/shell nanoparticles (dots-in rods) with a spherical CdSe core surrounded by a rod-like CdS shell, blinking effects, multi-excitonic emission and polarization of the emitted photons can be separately controlled by tuning the shell dimensions. This allows an unprecedented capability in radiative channels engineering, making dot-in-rods very efficient blinking-free sources of polarized single photons on-demand.

Actin is a major protein of the cytoskeleton which takes part into many cell processes like cell division, migration, morphogenesis… For example, in response to migration signaling, the cell induces the polymerization of an actin branched network towards the plasma membrane. This growing network exerts a pushing force against the membrane, leading to cell protrusion, the first step of cell migration. This process requires a tight regulation of the actin network in time and space. Such complexity has raised interest from both physics and biology communities, thus leading to studies combining interdisciplinary approaches. Here, I will describe two studies showing the versatile function of a specific actin structure, the actin branched network generated by the Arp2/3 complex, depending where actin assembly is triggered. In a first part, I will show an in vitro approach in which we reconstituted the branched actin array at the surface of giant unilamellar vesicles (GUVs) by anchoring an actin activator to the GUV surface. The growth of the actin network from the GUV surface induces GUV propulsion. Our macroscopic observations of actin-propelled GUVs shed light on molecular details of the mechanism of actin-based motility. We showed that efficient continuous propulsion is due to the right balance between the free diffusion of the actin activator at the GUV surface and its segregation while it is transiently interacting with the actin network, a balance which is controlled by the Arp2/3 complex [1]. In a second part, I will describe a cell biology approach in which analyzed the role of actin in intracellular transport. We studied the distribution of the actin activator on endosomal membranes, the WASH complex. Our observations suggest that actin contributes to the dynamic exchange of the activator between the cytosol and the endosomes. Moreover, we showed that actin polymerization regulates the organization of WASH into small and discrete domains at the surface of endosomes. Our data suggest a potential role of actin in proteo-lipidic domain compartmentalization of endosomes, a precursor step to endosomal sorting [2]. [1] Arp2/3 controls the motile behavior of N-WASP-functionalized GUVs and modulates N-WASP surface distribution by mediating transient links with actin filaments. V. Delatour*, E. Helfer*, D. Didry, K. H. D. Lê, J.-F. Gaucher, M.-F. Carlier, G. Romet-Lemonne. Biophys. J. 94, 4890-4905 (2008) [2] Actin polymerization controls the organization of WASH domains at the surface of endosomes. E. Derivery*, E. Helfer*, V. Henriot, A. Gautreau. PLoS One 7, e39774 (2012)

End tethered polymer chains have been recognized to be excellent adhesion promoters at polymer or are known to be able to modify the friction at interfaces. In this talk, we will present 2 related sets of experiments on the dynamics of polymer close to an interface. We will present results of polymer chains in contact with a melt and in contact with an elastomer. In a first part, we will present neutron reflectivity experiments characterizing the density profiles and dynamics of interdigitation between H-PS brushes, in contact with d-PS thick layers, heated above their glass transition temperature. This interdigitated brushes will be shared and disentangled from the melt leading to a large slip at the interface. The density profiles of the sheared brushed will be presented. In a second part we will present some friction measurement at a PDMS chains – PDMS elastomer interface and we will show that the grafted chains penetration and dynamics allows to control the friction at such elastomer interfaces.

Even if theoretically discovered long ago, the dilaton, the Goldstone-boson of spontaneous breaking of scale (conformal) invariance, is still subject of active investigations. These not only concern its theoretical applications, such as the a-theorem in four dimensions, but also phenomenological ones. In this talk I will review some of the potential manifestations of the dilaton in Nature: at the electroweak scale in relation to the recently discovered Higgs-like particle, and in cosmology owing to its connection with the energy of the vacuum.

A very interesting quantity that can be measured in the simulations of atomistic models of supercooled liquids is the free energy cost V(q) to keep two configurations at a given distance in phase space, namely at a given overlap "q". In my talk I will illustrate one of the techniques that can be used to measure numerically the thermodynamic potential V(q), and how we applied it to a 3d system of particles interacting via a modified Lennard-Jones potential. In particular I will discuss how from V(q) we extracted the amorphous surface tension, a quantity which, according to the Random First-Order Transition theory for the glass transition, is a master piece in the thermodynamic description of supercooled liquids. I will also show how the numerical study of correlations functions like < V(q) V(q') > gives us a direct way to test one of the most intriguing assumptions on the thermodynamics of supercooled liquids, i.e. the presence of some "self-induced" disorder in the low temperature phase.

I will review supersymmetric localization techniques, focusing on two-dimensional gauge theories. I will then apply them to the computation of the supersymmetric partition function on the sphere and the torus, producing matrix models. I will finally make connections with vortex partition functions, Gromov-Witten invariants, cluster algebras and the elliptic genus.

The CNRS/Solvay Joint Laboratory (UMR: Unité Mixte de Recherche) 'Advanced Polymer Materials Laboratory' (LPMA), located near Lyon, France, has been created in September 2006. Thanks to the fundamental research work developed in the lab, Solvay intends to propose innovative materials with tailored properties to answer to three main challenges: lightweight solutions for transportation, enhanced barrier properties for environmental safety and mastering of the life cycle of engineering plastics and rubbers. To achieve these challenging goals, the lab gathers CNRS researchers, who pursue academic careers, and Solvay researchers, shaping potential industrial applications. In this talk I will explain briefly how the lab works and how our strategy tackles topics relevant to applications and industrial issues by developing entirely new ideas relevant to fundamental concepts of polymer physics. I will exemplify this strategy by focusing on our recent developments on molecular modeling on silica filled rubbers and on our experimental work on the understanding of polymer blends.

I consider the concept of geometrical CP violation focusing on Delta(27) models. I discuss the scalar potential responsible for the spontaneous CP violation with calculable phases and give details on the issues that arise when introducing fermions compatible with geometrical CP violation. The minimal model with viable quark masses will be introduced as well as structures that lead to the observed lepton masses and mixing, which combined provide an existence proof of geometrical CP violation models accounting for the masses and mixing of all fermions.

The problem of the solid fracture has occupied scientists and engineers for centuries. This phenomenon is classically addressed within the framework of continuum mechanics. Still, stress enhancement at crack tips makes the failure behavior observed at the continuum-level scale extremely dependent on the presence of microstructure inhomogeneities down to very small scales. This yields statistical aspects which, by essence, cannot be addressed using the conventional engineering continuum approaches. I addressed this problem from two different points. First, I designed an experimental setup that allows growing well-controlled tensile cracks in brittle heterogeneous solids of tunable microstructure, over a wide range of loading speed. The crack dynamics and the evolution of stored and released mechanical energy are monitored in real time. In parallel, the acoustic emission going along with crack growth is recorded via a series of acoustic transducers, and analyzed in a way similar to that develop by geophysicists to process seismic signals. The experiments allowed me to characterize quantitatively the crackling dynamics of cracks, also to evidence intriguing statistical similarities between the seismicity associated with this simple situation of a single running crack under tension and the much more complex situation of multicracking in compressive fracture and in earthquakes. In parallel, I addressed the problem numerically. The simulations invoke a recent statistical model mapping heterogeneous fracture with the depinning transition of an elastic manifold in a random potential. The numerical exploration of the parameter space allowed me to unravel when (i.e. which loading conditions, microstructure material parameters, material constants...) regular dynamics compatible with continuum approaches are expected to be observed, and when crackling dynamics calling for statistical approaches are observed. In this latter case, we have characterized quantitatively the dynamics statistic and its variations as a function of the input parameters.