Experimental Observation of Topological Quantum Criticality
preprintposted on 2023-01-17, 17:00 authored by Sonja Barkhofen, Syamsundar De, Jan Sperling, Christine Silberhorn, Alexander Altland, Dmitry Bagrets, Kun Woo Kim, Tobias Micklitz
We report on the observation of quantum criticality forming at the transition point between topological Anderson insulator phases in a one-dimensional photonic quantum walk with spin. The walker's probability distribution reveals a time-staggered profile of the dynamical spin-susceptibility, recently suggested as a smoking gun signature for topological Anderson criticality in the chiral symmetry class AIII. Controlled breaking of phase coherence removes the signal, revealing its origin in quantum coherence.