X-ray parametric down-conversion at an XFEL
Understanding and harnessing X-ray quantum effects could open new, to our knowledge, frontiers in imaging and quantum optics. In this study, we measured the process of X-ray parametric down-conversion, where a single high-energy X-ray photon splits into two lower-energy photons. Using the SACLA X-ray free electron laser in Japan at 9.83 keV, we found clear evidence that pairs of photons were produced along the energy-angle relationship that conserved both energy and momentum, as predicted for down-conversion, and consistent with quantum entanglement of X-ray photons. By matching specific photon pairs for energy and momentum conservation, we observe a signal rate of 1250 pairs per hour, confirming that correlated photon pairs can be generated and observed in the absence of explicit time correlations. Our results show that with further refinement, the number of entangled photons produced per laser pulse could increase by an order of magnitude. This paves the way for demonstrating quantum-enhanced X-ray imaging, and confirmation of X-ray photon entanglement.
Authors
- N. J. Hartley (ORCID: https://orcid.org/0000-0002-6268-2436)
- Taito Osaka (ORCID: https://orcid.org/0000-0003-0545-9737)
- Richard L. Sandberg (ORCID: https://orcid.org/0000-0001-9719-8188)
- S. Shwartz (ORCID: https://orcid.org/0000-0002-9511-4224)
- Norimasa Ozaki (ORCID: https://orcid.org/0000-0002-7320-9871)
- Aliaksei Halavanau (ORCID: https://orcid.org/0000-0002-5879-9578)
- S. H. Glenzer (ORCID: https://orcid.org/0000-0001-9112-0558)
- Abigail Hardy Carpenter (ORCID: https://orcid.org/0000-0002-1252-1765)
- Naoki Yamagata (ORCID: https://orcid.org/0000-0001-9102-9631)
- Hussain Jeevakhan (ORCID: https://orcid.org/0000-0001-7121-3087)
- Kazuhisa Taketoshi
- Scott Curtis (ORCID: https://orcid.org/0000-0002-5510-4566)
- James Baxter
- Okhura Daisuke
Institutions
- Brigham Young University (US)
- Bar-Ilan University (IL)
- SLAC National Accelerator Laboratory (US)
- SPring-8 (JP)
- The University of Osaka (JP)
Publication Details
- Journal
- Optica
- Published
- 2025-05-19
- DOI
- https://doi.org/10.1364/optica.560275
- Citations
- 1
- Primary Topic
- Advanced X-ray Imaging Techniques
- Type
- article
- Field-Weighted Citation Impact
- 1.88
Funders
- Israel Science Foundation
- Japan Society for the Promotion of Science
- Basic Energy Sciences
- Fusion Energy Sciences