QUINTO · Quantum INteracting Topological Optics

Atom-light interfaces are vital for a range of potential applications in the coming “second quantum revolution”, from secure communication to ultra-precise sensors to quantum computers. A new exciting possibility is to arrange atoms in dense, regular arrays, where wave interference leads to strong collective emission. This property has been shown to polynomially or even exponentially improve the efficiency of single-photon-level applications. A frontier still awaiting a breakthrough is in the many-body regime, in particular, to expand the realm of atom arrays interacting with light toward realizing and studying exotic strongly correlated behavior.In QUINTO (Quantum INteracting Topological Optics), we will propose routes by which such systems can realize many-body states featuring topological order (TO). TOs have attracted significant interest due to wide-ranging implications ranging from possible fault-tolerant quantum computing to surprising fundamental properties such as the emergence of “anyonic quasi-particles” (being neither bosons nor fermions) and emergent lattice gauge theories. We will use the known physics of TOs within condensed matter physics as a “window” to developing the concept of many-body quantum optics, and show that, in turn, the arrays provide new ways of creating, understanding and measuring TOs.We will employ innovative, condensed-matter-inspired theoretical and numerical techniques, breaking state-of-the-art limitations (e. g. on system size), to study two routes towards quantum-optical TOs: arrays in optical cavities and “topological bands” in free-space arrays. We aim to: (i) demonstrate that long-range interactions, induced by emission and re-absorption of photons, provides a new paradigm for inducing TOs, (ii) elucidate the influence of such interactions on fundamental TO physics, and (iii) show that the output light carries information sufficient to detect a TO (including signatures of anyons).