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Q: Fachverband Quantenoptik und Photonik
Q 32: Photonics and Biophotonics II
Q 32.5: Talk
Wednesday, March 4, 2026, 15:30–15:45, P 3
Experimental measurement of the non-Abelian Quantum Geometric Tensor in a multiband photonic lattice — •Martin Guillot1, Cédric Blanchard1, Martina Morassi1, Aristide Lemaître1, Luc Le Gratiet1, Abdelmounaim Harouri1, Isabelle Sagnes1, Robert-Jan Slager2, F. Nur Ünal3, Jacqueline Bloch1, and Sylvain Ravets1 — 1Center for Nanoscience and Nanotechnology, CNRS, Paris-Saclay university, 91120 Palaiseau, France — 2Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom — 3School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
Recent discoveries in semi-metallic multi-gap systems featuring band singularities have galvanized enormous interest in particular due to the emergence of non-Abelian braiding properties of band nodes. This previously uncharted set of topological phases necessitates novel approaches to probe them in laboratories, a pursuit that intricately relates to evaluating non-Abelian generalizations of the Abelian quantum geometric tensor (QGT) that characterizes geometric responses.
In this talk, we present the first direct measurement of the non-Abelian QGT. We achieve this by implementing a novel orbital-resolved polarimetry technique to probe the full Bloch Hamiltonian of a six-band two-dimensional (2D) synthetic lattice, which grants direct experimental access to non-Abelian quaternion charges, the Euler curvature, and the non-Abelian quantum metric associated with all bands
Keywords: Topology; Photonic lattices; Polaritons