Witnessing Light-Driven Entanglement using Time-Resolved Resonant Inelastic X-Ray Scattering

Quantum computing takes advantage of principles of quantum mechanics, specifically entanglement, to encode information, which in turn requires characterizing and controlling entanglement within these materials. However, defining a figure of merit for entanglement within a material is both theoretically and experimentally challenging. At equilibrium, extracting entanglement witnesses from spectroscopies is feasible, but this approach cannot be directly extended out of equilibrium and is incompatible with laser control of materials. Here, we propose a systematic approach to quantify the time-dependent entanglement of transient states of quantum materials through time-resolved resonant inelastic x-ray scattering(trRIXS). We demonstrate the efficiency of our approach using a quarter-filled extended Hubbard model(EHM), and predict light-enhanced quantum entanglement that we attribute to the proximity to a phase boundary. This work sets the stage for experimentally witnessing and controlling entanglement in light-driven quantum materials via solid-state accessible ultrafast spectroscopic measurements.