Coherent kiloelectronvolt x-rays generated by subcycle optical drivers: a feasibility study

We theoretically explored the feasibility of high-harmonic generation in the kiloelectronvolt spectral range by optical waveforms of durations progressively shortened from multicycle to subcycle. Our study revealed that subcycle optical pulses offer a clear advantage in generating isolated x-ray attosecond pulses. In combination with their sub-fs optical drivers these pulses will open the route for x-ray attosecond pump-optical attosecond probe experiments, advancing attosecond streaking and attosecond absorption techniques to new realms of investigation of electronic processes.