Light control of the optical nonlinearity of a driven quantum chain*

Intense ultrashort electromagnetic fields have enabled the observation and control of spectacular light-driven emergent phenomena such as transient superconducting-like phases, charge ordering, and excitonic condensation. A particularly intriguing platform for such studies are quasi-one-dimensional Mott insulators, where light-matter interaction is predicted to modify effective many-body interactions and lead to exotic nonequilibrium ordering phenomena such as eta-pairing superconductivity. Here, we investigate a paradigmatic quantum chain, the quasi-one-dimensional cuprate compound Sr₂CuO₃. We find that intense mid-infrared excitation reshapes the many-body states contributing to its large optical nonlinearity, resulting in a dramatic transientreshaping of its harmonic emission spectrum. I will discuss how these observations may be rationalized by a light-driven renormalization of effective interactions, and its implications for the realization of long-range-ordered phases in light-driven quantum materials.