Energy coupling during relativistically intense laser–matter interactions is encoded in the attosecond motion of strongly driven electrons at the pre-formed plasma–vacuum boundary. Studying and controlling this motion can reveal details about the microscopic processes that govern a vast array of light–matter interaction phenomena, including those at the forefront of extreme laser–plasma science such as laser-driven ion acceleration1, bright attosecond pulse generation2,3 and efficient energy coupling for the generation and study of warm dense matter4. Here we experimentally demonstrate that by precisely adjusting the relative phase of an additional laser beam operating at the second harmonic of the driving laser it is possible to control the trajectories of relativistic electron bunches formed during the interaction with a solid target at the attosecond scale. We observe significant enhancements in the resulting high-harmonic yield, suggesting potential applications for sources of ultra-bright, extreme ultraviolet attosecond radiation to be used in atomic and molecular pump–probe experiments5,6.
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This work was supported by the European Regional Development Fund (EFRE), Deutsche Forschungsgemeinschaft (SFB TR18-A7), UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/I029206/1 and by Laserlab Europe. This project has received funding from the European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement no. 641272. The authors acknowledge the computing time granted by the John von Neumann Institute for Computing (NIC) and provided on the super-computer JURECA at Jülich Supercomputing Centre. B.D. acknowledges support from the EPSRC through grants and a Career Acceleration Fellowship. S.R. acknowledges support from the Helmholtz Association (Young Investigator's Group VH-NG-1037). C.R. acknowledges support from the VolkswagenStiftung. The authors acknowledge the assistance of F. Ronneberger and B. Beleites as laser operators.
The authors declare no competing financial interests.
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Yeung, M., Rykovanov, S., Bierbach, J. et al. Experimental observation of attosecond control over relativistic electron bunches with two-colour fields. Nature Photon 11, 32–35 (2017). https://doi.org/10.1038/nphoton.2016.239
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