GP2 - Birmingham Workshop Program: Probing Abelian and non-Abelian Topology in Polariton Lattices

Session Information

Location: Physics West 117 | School of Physics and Astronomy, University of Birmingham
Day: 1. Tuesday 21st April
Time: 14:00-14:40
Chairperson: Chair: Iacopo Carusotto

Presentation Details

Presentation Type: Oral | Invited
Title: Probing Abelian and non-Abelian Topology in Polariton Lattices
Abstract: The direct measurement of electronic and photonic band structures is essential for uncovering the topological and geometric properties of engineered materials. In this work, we introduce two complementary approaches to fully characterize the quantum geometry of exciton polariton lattices.

First, we present a sublattice Stokes polarimeter, a measurement technique enabling the complete reconstruction of Bloch wavefunctions in bipartite photonic lattices. This method allows us to experimentally access the full Bloch Hamiltonian, and reconstruct the full quantum geometric tensor even near degeneracies where conventional techniques fail. The approach is generalizable to systems with multiple internal degrees of freedom, paving the way for probing more complex topological structures in multiband settings.

Second, we extend our investigation to non-Abelian topology in multi-gap photonic lattices. We demonstrate the measurement of non-Abelian Berry curvature and the full non-Abelian quantum metric in a six-band photonic lattice, directly retrieving the Euler class topological invariant. Our results reveal pairs of nodes with non-trivial Euler class, demonstrating topological obstruction against annihilation due to braiding, which is a hallmark of non-Abelian charges. This work opens exciting prospects in view of manipulating non-Abelian topological charges and implementing braiding protocols in photonic systems.

Presenter

Prof Sylvain Ravets
Center for Nanoscience and Nanotechnology, CNRS, Paris–Saclay university | France

Authors

1. Ravets, Sylvain | Center for Nanoscience and Nanotechnology, CNRS, Paris–Saclay university