Witnessing nonequilibrium multipartite entanglement by time-resolved resonant inelastic X-ray scattering

Characterizing and controlling entanglement in quantum materials is crucial to facilitate the progress of quantum technologies. However, defining a quantifiable measure of multipartite entanglement within solids of many-body quantum systems is a challenging task both in theory and experiments. Motivated by the recent progress in equilibrium entanglement witnesses, we propose a protocol to extract the time-resolved QFI far from equilibrium via the time-resolved resonant inelastic X-ray scattering (trRIXS). We then apply our method to a material-relevant model and predicted light-induced enhancement of entanglement. Such an enhancement is amplified by the non-local interactions in the many-body system. With concrete spectral predictions and material-relevant models, our simulations provide guidance for further light-control of entanglement in materials.