Experimental demonstration of attosecond hard X-ray pulses
Abstract
We present the first direct experimental confirmation of attosecond pulse generation in the hard X-ray regime with a free-electron laser. Our experiment is based on measurements of a nonlinear optical phenomenon known as amplified spontaneous emission (ASE) from 3d transition metals. By analyzing the yield of the collective X-ray fluorescence induced by ultrashort pulses at the Linac Coherent Light Source, we identify the generation of attosecond pulses and shot-to-shot fluctuations in their duration, ranging from 100 as to 400 as. The observed product of bandwidth and pulse duration for 100 as pulses is approximately 2 fseV, indicating the generation of nearly transform-limited pulses. Our results extend the photon energy reach of attosecond techniques by one order of magnitude, providing the ability to simultaneously probe matter on the time-scales of electronic phenomena and with atomic spatial resolution. Furthermore, attosecond hard X-ray pulses can outrun the fastest radiation damage processes, paving the way to single-shot damage-free X-ray measurements.
Keywords
Cite
@article{arxiv.2506.07968,
title = {Experimental demonstration of attosecond hard X-ray pulses},
author = {Ichiro Inoue and River Robles and Aliaksei Halavanau and Veronica Guo and Thomas M. Linker Andrei Benediktovitch and Stasis Chuchurka and Matthew H. Seaberg and Yanwen Sun and Diling Zhu and David Cesar and Yuantao Ding and Vincent Esposito and Paris Franz and Nicholas S. Sudar and Zhen Zhang and Taito Osaka and Gota Yamaguchi and Yasuhisa Sano and Kazuto Yamauchi and Jumpei Yamada and Uwe Bergmann and Matthias F. Kling and Claudio Pellegrini and Makina Yabashi and Nina Rohringer and Takahiro Sato and Agostino Marinelli},
journal= {arXiv preprint arXiv:2506.07968},
year = {2025}
}