Spin-orientation-resolved attosecond chronoscopy in strong field ionization

Abstract: Attosecond chronoscopy represents a major breakthrough in the study of ultrafast phenomena and has the potential to revolutionize our understanding of the fundamental physics of matter. We theoretically investigate the spin-orientation-resolved attosecond chronoscopy for the first time by the circular RABBIT technique for Kr atoms. Due to the spin-orbit interaction and the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state, the spin-resolved ionization rates of photoelectrons emitted from $^2P_{1/2}$ and $^2P_{3/2}$ channels can be expressed via $m$-resolved ionization rates of initial state, where $m$ is the orbital magnetic quantum number. We demonstrate that the yields difference between spin-up and spin-down photoelectrons from each channel are closely associated with the different behaviors of corresponding Wigner time delay. We find that the Wigner time delay between spin-up and spin-down photoelectrons in the polarization plane can reach several tens of attoseconds in the co-rotating geometry, but a few attoseconds in the counter-rotating geometry. Our approach opens up a new avenue for probing the spin-dependent behavior of Wigner time delay, and lays the foundation for spin-orientation-resolved attosecond chronoscopy, which can be verified by the current experimental techniques.