K hexagonal lattice

We are developing novel experimental techniques to study genuine out-of-equilibrium topological phases of matter in periodically-driven optical lattices.

Floquet topological phases & topological edge modes

Floquet engineering not only enables the realization of model Hamiltonians beyond static systems, but also the creation of novel phases of matter with no static analog. A striking example is 2D systems with zero Chern numbers that still host topologically protected chiral edge modes - known as anomalous Floquet topological systems. These are described by a generalized bulk-boundary correspondence that extends the static case, linking bulk topology to edge mode structure.

Schematic of the periodically-driven honeycomb lattice, where the tunneling bonds a varied in strength.

We developed a periodic driving protocol in hexagonal optical lattices by modulating the three tunnel couplings over time. This scheme hosts a variety of distinct Floquet topological regimes, including conventional and anomalous Floquet topological phases. To reveal their anomalous nature we developed a protocol to directly probe topological edge modes. To this end, we generate a topological interface by projecting a repulsive potential into the atomic plane. A tweezer trap, positioned near the interface, hosts a localized BEC, which after switching of the tweezer populates the edge mode revealing the chiral dynamics characteristic of topological edge modes. Unlike in solid-state systems, we can precisely control boundary shape and sharpness, which allows for precise studies of edge mode properties. By combining edge-mode observations with bulk measurements, such as Chern numbers, we were able to directly demonstrated the existence of anomalous Floquet topological phases.

 

PhD theses from our team:

Experimental results

Below you find a list of our most recent experimental results on studying Floquet topological phases.

Numerical & theoretical work

Here we collect research from our group that we performed together with our theory colleagues in order to develop a better understanding of the quantum many-body systems we are planning to study.

The team

  • Christoph Braun, Senior Scientist
  • Dizhou Xie, PostDoc
  • Johannes Arceri, PhD
  • Moritz Hornung, PhD

Former members:

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