X-ray cavity quantum optics with inner-shell transitions has been hindered by the overlap between resonant and continuum states. Here, we report the first experimental demonstration of cavity-controlled co-to-core resonant inelastic x-ray scattering (RIXS). We eliminate the effects of the absorption edge by monitoring the RIXS profile, thereby resolving the resonant state from the overlapping continuum. We observe distinct cavity-induced energy shifts and cavity-enhanced decay rate in the 2p3d RIXS spectra of WSi2. These effects, manifesting as stretched or shifted profiles in the RIXS planes, enable novel spectroscopic applications by cavity-controlled core-hole states. Our results establish core-to-core RIXS as a powerful tool for manipulating inner-shell dynamics in x-ray cavities, offering new avenues for integrating quanutm optical effects with x-ray spectroscopy.
@article{arxiv.2508.19384,
title = {Cavity Controls Core-to-Core Resonant Inelastic X-ray Scattering},
author = {S. -X. Wang and Z. -Q. Zhao and X. -Y. Wang and T. -J. Li and Y. Su and Y. Uemura and F. Alves Lima and A. Khadiev and B. -H. Wang and J. M. Ablett and J-P. Rueff and H. -C. Wang and O. J. L. Fox and W. -B. Li and L. -F. Zhu and X. -C. Huang},
journal= {arXiv preprint arXiv:2508.19384},
year = {2026}
}