Unconventional topology with a Rashba spin-orbit coupled quantum gas
Lecturer: Dimitris Trypogeorgos - CNR-INO BEC Center and Dipartimento di Fisica, Università di Trento
Date: Feb. 13, 2020 2:30 p.m. - 5 p.m.
Location: Querzoli
Organizer: Modugno Giovanni

Topological order can be found in a wide range of physical systems, from crystalline solids, photonic meta-materials and even atmospheric waves to optomechanic, acoustic and atomic systems. Topological systems are a robust foundation for creating quantized channels for transporting electrical current, light, and atmospheric disturbances. These topological effects are quantified in terms of integer-valued invariants, such as the Chern number, applicable to the quantum Hall effect, or the â„¤2 invariant suitable for topological insulators. Here we engineered Rashba spin-orbit coupling for a cold atomic gas giving non-trivial topology, without the underlying crystalline structure that conventionally yields integer Chern numbers. We validated our procedure by spectroscopically measuring the full dispersion relation, that contained only a single Dirac point. We measured the quantum geometry underlying the dispersion relation and obtained the topological index using matter-wave interferometry. In contrast to crystalline materials, where topological indices take on integer values, our continuum system reveals an unconventional half-integer Chern number, potentially implying new forms of topological transport.