Séminaire de l'équipe Photonique par Marcel Clerc

Le 23 juin, Marcel Clerc, Professeur à l’Université du Chili, donne un séminaire sur le thème :  “Topological transition at room temperature in out-of-equilibrium liquid crystal cell" à l'IRCICA à 11H. 

Un moment de convivialité est prévu après le séminaire. 

Voici le résumé:

Matter under different equilibrium pressure and temperature conditions exhibits different states such as solid, liquid, gas, and plasma. 
Exotic states of matter, such as Bose–Einstein condensates, superfluidity, chiral magnets, superconductivity, and liquid crystalline blue phases, 
are observed in thermodynamic equilibrium. Rather than being a result of an aggregation of matter, their emergence is due 
to a change in the topological state of the system. These topological states can persist out of thermodynamic equilibrium. 
This talk will discuss the macroscopic topological states of matter in a system with injection and energy dissipation using oscillatory forcing. 
In an experiment involving a liquid crystal cell under a low-frequency oscillatory electric field, 
we observe a transition from a non-vortex state to a state where vortices persist, a topological transition. 
Depending on the period and the type of the forcing, the vortices self-organise, forming square lattices, glassy states, and disordered vortex structures. 
Based on a stochastic amplitude equation, we identified the origin of the transition as the balance between stochastic creation and deterministic annihilation of vortices. 
Numerical simulations show topological transitions and the emergence of a square vortex lattice. 
Our results show that the matter maintained out of equilibrium using the temporal modulation of parameters can exhibit macroscopic exotic states.