Quasiparticles, flat bands, and exotic topology in hydrodynamic matter

We will discuss recently discovered collective phenomena in nonequilibrium soft matter systems and their links to basic notions of quantum matter—particularly quasiparticles and flat bands. In the first part of the talk, we will consider a 2D crystal made of hydrodynamically interacting particles. We will examine two pathways to the nonequilibrium melting of this hydrodynamic crystal, either by the excitation of ultrasonic quasiparticle avalanches or by the collisions of ultraslow flat-band phonons. Certain similarities and dissimilarities to graphene will be noted. In the second part of the talk, we will add elastic interactions to the hydrodynamics and see how this gives rise to rich non-Hermitian topological phenomena, such as bulk Fermi arcs.