Experimental verification of topologically induced vortices inside a billiard

Using flat electromagnetic resonators we experimentally verify the existenc e of vortices in the Poynting vector describing the energy transport in a r ectangular billiard. We show that these vortices appear as a consequence of the nontrivial topological structure of the underlying phase of the electr omagnetic field. The results are also relevant for vortices appearing durin g the quantum transport.