Emergent topological excitations in systems of ultracold dipolar particles
Systems with Weyl and Dirac quasiparticles have been predicted to display a plethora of novel fascinating phenomena, such as chiral anomaly, Fermi arcs on the surfaces, non-Anderson disorder-driven transitions, etc. Over the last several years enormous research efforts have been directed at finding new Weyl (Dirac) semimetals in solid-state systems and ways to realise them in ultracold atomic gases. In this talk, I will demonstrate that excitations with Weyl dispersion generically exist in 3D systems of dipolar particles in the presence of magnetic field. They emerge due to the dipolar-interactions-induced transitions between the J = 0 and J = 1 angular-momentum states of the particles. I will present microscopic calculations of the quasiparticle dispersion for systems of alkaline-earth atoms in optical traps and discuss methods of their experimental observation. Also, I will discuss excitations in 2D systems of dipolar particles and demonstrate the existence of long-wave excitations (chirons) with the dispersion of bilayer graphene in such systems.