Published: 9 May 2016, 13:19
Together with colleagues from the DESY in Hamburg, the Helmholtz-Instiute Jena and the European Synchrotron Radiation Facility in Grenoble, ACP principal scientist Gerhard Paulus has just published an original research article titled "Collective strong coupling of X-rays and nuclei in a nuclear optical lattice" in Nature Photonics (Haber et al., Nature Photon., doi: 10.1038/nphoton.2016.77, 2016).
Abstract: The advent of third-generation synchrotron radiation sources and X-ray free-electron lasers has opened up the opportunity to perform quantum optical experiments with high-energy X-rays. The prime atomic system for experiments in this energy range is the strongly nuclear resonant 57Fe Mössbauer isotope. Experiments have included measurements of the collective Lamb shift, observation of electromagnetically induced transparency, subluminal propagation of X-rays and spontaneously generated coherences. In these experiments, however, the nuclei were only weakly coupled to the light field. Collective strong coupling of nuclei and X-rays, which is desirable for many quantum optical applications, has eluded researchers so far. Here, we observe collective strong coupling between X-rays and matter excitations in a periodic array of alternating 57Fe and 56Fe layers. Our experiment extends the range of methods for X-ray quantum optics and paves the way for the observation and exploitation of strong-coupling-related phenomena at X-ray energies.