3D hybrid perovskites are currently superstar materials for photovoltaics and attract increasing attention of the scientific community. They also revealed attractive photoluminescence, as already well known for 2D layered hybrids. Our scientific approach is based on solid-state physics concepts originally developed for conventional semiconductors. The broad light-harvesting abilities and attractive transport properties of metal-halide hybrid perovskites can be related to their band structure.

Nanoparticles have significant advantages for biomedical applications, especially for the vectorization (possibly traceable) of active biomolecules, for labeling, or even as probes of some physicochemical parameters at the nanoscale. The diamond nanocrystal (nanodiamond) is a remarkable system with intrinsic properties allowing all these applications simultaneously. We will show that nanodiamonds rendered fluorescent by the creation of embedded color centers, can be used to measure the intraneuronal transport parameters in cultured neurons. Thanks to the high brightness and the excellent stability of nanodiamond photoluminescence we were able to correlate intraneuronal transport abnormalities to subtle genetic alterations found in neuropsychiatric disorders. Such an approach could provide an unbiased diagnosis of these complex diseases. In an other biomedical application, still in cultured cells, we used nanodiamond coated with cationic polymer to transport therapeutic oligonucleotides (RNAi) against the sequence of a junction oncogene responsible for Ewing sarcoma (a rare bone cancer). Compared to a conventional approach, the vectorization of the interfering RNA by the nanodiamond lead to a stronger inhibition of the oncogene responsible of cell proliferation. We will conclude by in vivo prospects of these two applications (transport intraneuronal and nanomedicine), and present several imaging modalities of nanodiamonds allowing their detection in tissues with highly reduce autofluorescence background.

Droplet-based microfluidics operates with liquids encapsulated and conveyed in droplets, as opposed to single phase microfluidics, where fluids are confined and transported directly in microchannels. The development of the droplet based microfluidics has been fostered by a series of contributions, made in the years 2000-2003,This early period was followed by a boost of biotechnological applications. Droplet based microfluidics is to-day an important branch of microfluidics. Here I will focus on droplets of colloidal sizes, i.e around one micrometer in diameter. I will show how to produce simple and multiple droplets of that size in microfluidic devices, how to assemble them and form basic bricks for future material applications, how to use them for delivering drugs in vivo, and how to manipulate them on chip.

The main aim of this talk is to introduce and review some of the recent developments in the theoretical and mathematical aspects of the non-equilibrium statistical mechanics of geophysical flows. This domains, at the intersection between statistical mechanics, turbulence and climate applications is a wonderful new playground for theoretical and mathematical physicists. Path integrals, instanton theory, semiclassical approximations, large deviation theory, and diffusion Monte-Carlo algorithms are at the core of our approach. Many natural and experimental turbulent flows display a bistable behavior: rare and abrupt dynamical transitions between two very different subregions of the phase space. The most prominent natural examples are probably the Earth magnetic field reversals (over geological timescales), the Kuroshio current bistability. Recent results show that a similar bistability occurs also in the turbulent dynamics of atmosphere jets, for instance on Jupiter's troposphere. Those abrupt transitions are extremely rare events that change drastically the nature of the flow and are thus of paramount importance. We will discuss those phenomena from a theoretical physics point of view, mainly in relation with large deviation theory.

Nearly 20 years ago Zudov et al. experimentally discovered huge microwave-induced resistance oscillations (MIRO) in high-mobility two-dimensional electron gas at low temperatures and moderate magnetic fields. This spectacular phenomenon has attracted a lot of interest. The mainstream theories describe MIRO as a quantum phenomenon and deal with quantum transitions between Landau levels in the presence of different types of disorder. In contrast, we show that MIRO is a purely classical memory effect caused by re-collisions of electrons with scattering centers after a cyclotron period. We develop a novel Drude-like approach to magneto-transport in presence of a microwave field, taking account of memory effects, and find an excellent agreement between numerical simulations, analytical results, and experiment.

I will describe experiments using soap films and soap bubbles to illustrate the interest of these common objects to some fluid mechanics problems. The flow in the very thin layer of these films is basically two dimensional and this property brings fundamental differences with fluid flows in three dimensions as well as experimental simplification. I will use three examples for this talk: the interaction between a flow and different structures in fast flowing soap films, the measurement of viscous drag in turbulent soap film channels, and thermal convection in soap bubbles. In all these cases, the two dimensional nature of the flow allows to capture some of the key features of the underlying dynamics such as a symmetry breaking mechanism leading to locomotion of passive objects in the first case, the role of the structure of the turbulence on the scaling of the viscous drag in the second case, and the appearance of large scale vortices in the last case.

A large class of materials, ranging from glasses to soft matter and biological systems, undergo structural arrest and physical aging. Following different experimental routes, like decreasing the temperature in a glass former liquid or increasing the packing fraction in a colloidal suspension, these materials can be driven in an out-of-equilibrium state, where their properties depend on the previous history of the system and spontaneously evolve with time. This process leads to an extremely complex dynamical scenario, characterized by a dramatic increase of the structural relaxation time and the emerging of multiple relaxation processes. The microscopic slow dynamics of out-of-equilibrium materials can be followed thanks to the unique properties of X-ray Photon Correlation Spectroscopy which probes the dynamics at the nanometric and atomic scale. Here I will present a detailed investigation of the relaxation processes occurring in metallic glasses during physical aging. Although the apparent differences, metallic glasses display an anomalous dynamics at the microscopic level which remembers that of complex soft materials, such as gels and concentrated colloidal suspensions. By combining dynamical and structural studies we have been able to quantitatively link for the first time this anomalous atomic motion to microscopic structural mechanisms usually observed in diffraction studies, providing a broader unique view of the glassy state.

Simply by looking at a duck swimming in a pond or a cargo ship moving on a calm sea, one can clearly tell that there is something common about their wake. Indeed, they both display a familiar V-shaped pattern which only differ from one another by their dimensions. In 1887, Lord Kelvin was able to provide a theory to explain the ship-wave pattern. His most popular achievement was to prove that the wake created by a disturbance moving at a uniform pace is always delimited by a straight wedge with half-angle 19.5 degrees, independent of the velocity of the disturbance. Recently, Kelvin’s century old and well accepted theory was challenged, by that drawing the attention of the fluid dynamics community…

Topological Insulators are new states of matter. At first sight, these are just ordinary band insulators : an energy gap separates the energy of states occupied by electrons from unoccupied states. However, the ensemble of occupied electronic states possesses a non-intuitive property, known in mathematics as a topological property. Its existence is at the origin of the main physical characteristics of topological insulators: the existence of metallic states at their surface. Hence from a phenomenological point of view the topological insulators are insulating materials surrounded by a metallic surface. Moreover these surface metals are rather unique: their electrons behave as if they were massless relativistic particles. More precisely their motion is described by a Dirac equation usually associated with relativistic particles. This leads to several unique physical properties, some of them reminiscent of those of graphene. Recently, this relation between relativistic excitations and topological property triggered a large amount of work to identify other phases with analogous properties. Excitations described by a Dirac or Weyl equation of motion have now been found in bulk materials and not only at the surface of insulators.