title: Tunable Subluminal Propagation of Narrow-band X-Ray Pulses.
abstract: Group velocity control is demonstrated for x-ray photons of 14.4 keV energy via a direct measurement of the temporal delay imposed on spectrally narrow x-ray pulses. Subluminal light propagation is achieved by inducing a steep positive linear dispersion in the optical response of 57Fe Mössbauer nuclei embedded in a thin film planar x-ray cavity. The direct detection of the temporal pulse delay is enabled by generating frequency-tunable spectrally narrow x-ray pulses from broadband pulsed synchrotron radiation. Our theoretical model is in good agreement with the experimental data.
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: Kilian P
authors.initials: KP
authors.lastname: Heeg
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Haber
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schumacher
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Bocklage
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Wille
authors.affiliation: Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.|Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany.
authors.forename: Kai S
authors.initials: KS
authors.lastname: Schulze
authors.affiliation: Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.|Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Loetzsch
authors.affiliation: Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.|Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Uschmann
authors.affiliation: Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.|Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena, Germany.
authors.forename: Gerhard G
authors.initials: GG
authors.lastname: Paulus
authors.affiliation: ESRF-The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Rüffer
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Röhlsberger
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Evers