To content
Department of Physics

Adiabatic realization of anomalous Floquet topological systems

Parameter space of the tunable hexagonal lattices with the differences in tunneling elements J1, J2, J3 along the three bond directions and the offset Delta between the two sublattices © Luca Asteria
The figure shows the parameter space of the tunable hexagonal lattices with the differences in tunneling elements J1, J2, J3 along the three bond directions and the offset Delta between the two sublattices. The indicated path cannot be contracted without closing a band gap and it corresponds to the adiabatic realization of an anomalous Floquet topological system.
In a new article, we introduce an new way to realize anomalous Floquet topological systems via adiabatic sweeps.

In an international collaboration with Kyoto University, University of Hamburg and TU Berlin, we introduce a robust way to realize anomalous Floquet topological systems via adiabatic sweeps, thus connecting these topological systems to a two-dimensional generalization of Thouless charge pumps. Anomalous Floquet topology appears only in driven systems and breaks with the conventional bulk-boundary correspondence by providing chiral edge states even for topologically trivial bands. Usually one considers a drive at frequencies that are near-resonant with the system's bandwidth, where Floquet heating plays a significant role in interacting systems. In the new work, we show that anomalous Floquet topological phases can be realized in an adiabatic protocol, where the system is always in the instantaneous ground state and where Floquet heating is significantly suppressed. We realize the new concept in an experiment with ultracold rubidium atoms in a tunable hexagonal optical lattice and observe a robust response in the interacting system.

The preprint is available at Asteria et al.