% IMPORTANT: The following is UTF-8 encoded. This means that in the presence % of non-ASCII characters, it will not work with BibTeX 0.99 or older. % Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or % “biber”. @ARTICLE{Linker:625317, author = {Linker, Thomas M. and Halavanau, Aliaksei and Kroll, Thomas and Benediktovitch, Andrei and Zhang, Yu and Michine, Yurina and Chuchurka, Stasis and Abhari, Zain and Ronchetti, Daniele and Fransson, Thomas and Weninger, Clemens and Fuller, Franklin D. and Aquila, Andy and Alonso-Mori, Roberto and Boutet, Sebastien and Guetg, Marc W. and Marinelli, Agostino and Lutman, Alberto A. and Yabashi, Makina and Inoue, Ichiro and Osaka, Taito and Yamada, Jumpei and Inubushi, Yuichi and Yamaguchi, Gota and Hara, Toru and Babu, Ganguli and Salpekar, Devashish and Sayed, Farheen N. and Ajayan, Pulickel M. and Kern, Jan and Yano, Junko and Yachandra, Vittal K. and Kling, Matthias F. and Pellegrini, Claudio and Yoneda, Hitoki and Rohringer, Nina and Bergmann, Uwe}, title = {{A}ttosecond {I}nner-{S}hell {L}asing at {A}ngstrom {W}avelengths}, journal = {Nature}, volume = {642}, issn = {0028-0836}, address = {London [u.a.]}, publisher = {Nature Publ. Group}, reportid = {PUBDB-2025-01093, arXiv:2409.06914}, pages = {934 – 940}, year = {2025}, abstract = {Since the invention of the laser nonlinear effects such as filamentation, Rabi-cycling and collective emission have been explored in the optical regime leading to a wide range of scientific and industrial applications. X-ray free electron lasers (XFELs) have led to the extension of many optical techniques to X-rays for their advantages of angstrom scale spatial resolution and elemental specificity. One such example is XFEL driven population inversion of 1s core hole states resulting in inner-shell K$α$ (2p to 1s) X-ray lasing in elements ranging from neon to copper, which has been utilized for nonlinear spectroscopy and development of next generation X-ray laser sources. Here we show that strong lasing effects, similar to those observed in the optical regime, can occur at 1.5 to 2.1 angstrom wavelengths during high intensity (> ${10^{19}}$ W/cm${^{2}}$) XFEL driven inner-shell lasing and superfluorescence of copper and manganese. Depending on the temporal substructure of the XFEL pump pulses(containing ${~10^{6}}$ - ${10^{8}}$ photons) i, the resulting inner-shell X-ray laser pulses can exhibit strong spatial inhomogeneities as well as spectral splitting, inhomogeneities and broadening. Through 3D Maxwell Bloch theory we show that the observed spatial inhomogeneities result from X-ray filamentation, and that the spectral splitting and broadening is driven by Rabi cycling with sub-femtosecond periods. Our simulations indicate that these X-ray pulses can have pulse lengths of less than 100 attoseconds and coherence properties that open the door for quantum X-ray optics applications.}, keywords = {Optics (physics.optics) (Other) / Atomic Physics (physics.atom-ph) (Other) / FOS: Physical sciences (Other)}, cin = {FS-TUX}, ddc = {500}, cid = {I:(DE-H253)FS-TUX-20170422}, pnm = {631 - Matter – Dynamics, Mechanisms and Control (POF4-631) / AIM, DFG project G:(GEPRIS)390715994 - EXC 2056: CUI: Advanced Imaging of Matter (390715994) / HIDSS-0002 - DASHH: Data Science in Hamburg - Helmholtz Graduate School for the Structure of Matter $(2019_IVF-HIDSS-0002)$}, pid = {G:(DE-HGF)POF4-631 / G:(GEPRIS)390715994 / $G:(DE-HGF)2019_IVF-HIDSS-0002$}, experiment = {EXP:(DE-MLZ)NOSPEC-20140101 / EXP:(DE-MLZ)External-20140101}, typ = {PUB:(DE-HGF)16}, pubmed = {pmid:40500439}, eprint = {2409.06914}, howpublished = {arXiv:2409.06914}, archivePrefix = {arXiv}, SLACcitation = {$\%\%CITATION$ = $arXiv:2409.06914;\%\%$}, doi = {10.1038/s41586-025-09105-9}, url = {https://bib-pubdb1.desy.de/record/625317}, }