Control and emergence of collective order in random media

Par Nicolas Bachelard, Institute for Theoretical Physics, Vienna University of Technology, Austria

Mardi 3 septembre,  14h00, Salle des séminaires (215), 2e étage, Bât. A4N

Abstract :

In wave physics, random media are characterized by the existence of multiple degrees of freedom as well as a subsequent multiplicity of configurations. In this talk, I will present different approaches that I developed to harness the versatility of disordered systems and force the emergence of collective order out of random ensembles.
First, I will consider the case of strongly scattering media filled with optical gain that create random lasing emissions (and are referred to as random lasers). While the spectrum of random lasers is typically multimode—composed of many frequencies, here I will demonstrate that the interaction amongst modes can be controlled through wave-front-shaping technique in order to collectively build-up a singlemode emission at tunable frequency.
Then, I will show that random populations of mobile particles can be driven to self-organize into out-of-thermodynamic-equilibrium crystalline structures through the controlled dissipation of coherent energy. The elements individually synchronize their responses to dynamically develop collective properties such as resiliency abilities or the self-adaptation to the environment.

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