Physics - Condensed Matter Seminar

Thanks to their inherent robustness, topological materials are highly valuable for applications requiring stringent noise mitigation, from precision metrology to quantum information processing. Replicating this topological robustness in photonic systems has proven to be critically challenging, largely due to the bosonic nature of light. In this talk I will present recent experimental works from my group that offer a dual perspective on this challenge: fighting or embracing this lack of robustness. First, I will show how we observed a robust, quantized Hall drift of light by encoding the Haldane model in the synthetic frequency dimension of an optical fiber loop platform; there, breaking time-reversal symmetry was essential to provide genuine robustness. I will then invert this perspective and show how the inherent lack of robustness in bosonic topological models that preserve time-reversal symmetry can instead be harnessed as a resource, turning sensitivity to external perturbations into a metrological advantage. By encoding a bosonic analogue of the Kitaev model, we can detect weak perturbations with a signal-to-noise ratio that scales exponentially with system size. These results reveal new perspectives on the fundamental limits that constrain information flow in open quantum systems.