Prof. Dr. Beatriz Olmos Sanchez

An excited atom interacting with the radiation field decays by emitting a photon. This behaviour drastically changes in the case of an ensemble of atoms, as the emitters collectively couple to the radiation field. On one hand, the exchange of virtual photons induces dipole-dipole long-ranged interactions among the atoms. On the other hand, excitations in the ensemble can either decay extremely fast or remain stable over very long times due to the constructive or destructive interference of the decay channels, respectively. These collective phenomena, which are referred to as super and subradiance, were theoretically predicted already in the 1950s. However, only rather recently several experiments have unambiguously demonstrated these effects.

• The phenomenon of subradiance. Almost independently of the external geometry of the atoms, the atomic system features large subradiant manifold of states. I am particularly interested in exploting this for the long-lived transport of excitations through a atomic arrays. Moreover, these subradiant manifolds can be shown to be robust against disorder, including the motion induced by the temperature in an atomic gas.

• The coupling of atoms to surfaces, nanofibers, and other enviroments. While these fascinating phenomena can already be observed in atoms in free space, even richer physics is observed in the presence of nearby surfaces, nanospheres and metamaterials. These modify the electromagnetic field mode structure by imposing boundary conditions and thereby can change radically the radiative properties of a group of emitters. In particular, the coupling of atoms to photonic nanostructures, such as photonic crystals and optical nanofibers, has opened a new exciting research horizon. In recent works we began to address precisely these challenges for the case of a chain of atoms coupled to a nanofiber. I aim to, not only continue studying this experimental platform, but also use the expertise we have acquired to extend our investigations to other photonic nanostructures, which offer new and exciting possibilities, such as a controllable interaction range and the possibility of “switching on and off” the interactions between emitters.

• Topology in the presence of long range hoppings. Again based on the systems studied above, one can ideate situations that feature topological properties. However, here the dipole-dipole interactions are typically long-ranged, where topological concepts are not always well defined. I am interested in the characterization of topological properties and edge states in these situations.