Researchers realize an anomalous Floquet topological system

An international team led by physicists at the Ludwig-Maximilians Universitaet (LMU) in Munich realized a novel time-dependent topological system with ultra-cold atoms in optical honeycomb lattices.

The topological phases of matter have attracted much interest due to their unique electronic properties that often result in exotic surface or boundary modes, the existence of which is based on the non-trivial topological properties of the underlying system. In particular, the robustness of these properties makes them interesting for applications.

Periodic conduction has become an important technique to emulate the physics of uncontrolled topological solid state systems. The properties of powered topological systems, however, transcend those of their static counterparts. Using a 39K BEC loaded into a periodically modulated optic honeycomb network, we could generate a time-dependent topological system.

For certain modulation parameters, the system is in the so-called anomalous Floquet regimen, where the Chern numbers of all volume bands are equal to zero, while at the same time chiral edge modes exist in all quasi-energy spaces . These non-trivial topological properties come from the non-trivial winding of the quasi-energy spectrum and cannot occur in uncontrolled systems.

By combining the energy gap and local Hall deviation measurements, the full set of topological invariants describing the time-dependent system was experimentally determined for the first time, and the existence of chiral border modes could be revealed even in bounded geometry. soft. Due to its remarkable properties, especially in the presence of disorder, Floquet’s anomalous phase promises the realization of periodically powered interactive systems that can withstand a mass of many localized bodies, but thermalization edge modes, an intriguing unbalance . body phase that can be resistant to conventional Floquet heating.