Special CPM Seminar

Measurement of 2D topological invariants from anomalous edge spectral flow

Sriram Ganeshan

Simons Center for Geometry and Physics

In this work, we experimentally measure the 2D topological invariant of the integer quantum Hall effect in a photonic system by selectively manipulating and probing the edge. We exploit the “bulk-boundary correspondence” of the chiral edge modes in a photonic system which manifests itself as an anomalous edge spectral flow. This anomalous spectral flow associated to the chiral dynamics allows us to unambiguously measure topological invariants. This experiment provides a new approach for direct measurement of topological invariants, independent of the microscopic details, and thus could be extended to probe strongly-correlated topological orders.