Probing floquet topological phase transition in room-temperature superradiance lattices

Floquet modulation plays a crucial role in manipulating the phases of quantum matter. However, experimentally characterizing the Floquet topological phase transition, particularly in one-dimensional systems, remains challenging. In this study, we investigate the Floquet topological phase transition within the Su-Schrieffer-Heeger model in room-temperature superradiance lattices. Due to their resilience to thermal noise, superradiance lattices can undergo strong phase modulation to synthesize an effective AC electric field via Peierls substitution. Since the one-dimensional momentum-space Su-Schrieffer-Heeger model breaks time-reversal symmetry, we can classify the topologically distinct phases through optical nonreciprocity. We observe the topological phase transition induced by effective AC and DC electric fields, successfully mapping the complete phase diagram. Our results provide a novel spectroscopic approach to characterizing the topological phase transitions of Zak phases, which can contribute to the exploration of other non-equilibrium topological phases under strong modulation. Floquet engineering can flexibly manipulate the topological phases of matter, though experimentally characterizing these transitions is challenging. The authors create onedimensional Floquet superradiance lattices in room-temperature atoms and exploit the atomic-thermal-motioninduced optical nonreciprocity to map the topological phase diagram under various driving conditions.