Final Report Summary - SQMS (Synthetic Quantum Many-Body Systems)
In this project we experimentally explored key physics concepts, which had been invented to gain understanding of the behavior of many interacting quantum particles. We created and studied different synthetic quantum many-body systems by cooling atoms to a few Nanokelvins above absolute zero temperature and exposing them to interfering laser beams. The properties of such trapped quantum gases are governed by the interplay between atomic motion and a well characterized interaction between the particles. This conceptual simplicity is unique in experimental physics and provides a direct link between the experiment and the model describing the system. It enabled us to shine new light on a wide range of fundamental phenomena and address open challenges. We created an artificial form of graphene, in which the Dirac fermions are atoms travelling in a hexagonal interference pattern of laser light. By breaking the time-reversal symmetry of this system, we could experimentally realize a fundamental concept underlying topological insulators, the so-called topological Haldane model. Another direction of the project was the study of the Dicke model, which describes the coupling of an ensemble of two-level systems to a single mode light field. Using a Bose-Einstein condensate inside an optical cavity we synthetically created the model Hamiltonian and could observe a phase transition into a superradiant state which had long been predicted but never been observed. The third major direction of this project was to develop a toolbox for cold atoms, allowing us to study the concepts of mesoscopic physics, such as two-terminal measurements and quantized conductance.