Speaker
Description
Correlated strong-field double ionization exhibits a characteristic 'knee' structure in the double ionization yield as a function of intensity [1-3]. This feature arises because of the contribution from the nonsequential double ionization (NSDI) process, in which the electron-electron interaction rather than independent tunneling plays a key role.
Generally, NSDI enhancement is attributed to the rescattering of the first ionized electron at the parent ion, thereby transferring the second electron to an easily ionizable excited state or the continuum [4]. However, some experiments have observed an enhancement of NSDI also in elliptically polarized fields, challenging the conventional rescattering picture [5]. Full ab initio calculations of this two-electron problem have remained computationally challenging and, up to now, only a few promising results have become available for He [6]. In the present study, we address the challenge and perform fully correlated calculations of NSDI in strong fields by employing the multiconfigurational time-dependent Hartree-Fock method (MCTDHF) [7] for Be atoms and linearly polarized fields. Because of its low first ionization potential of 9.32 eV, Be is a prime candidate for an ab initio simulation. We utilize the two-particle reduced density matrix [8] and investigate the two-electron dynamics as a function of time and intensity. As the intensity increases, we see signatures of the rescattering process leading to an enhancement in the NSDI yields.
References
[1] D. N. Fittinghoff et al. Phys. Rev. Lett. 69, 2642–2645 (1992).
[2] B. Walker et al. Phys. Rev. Lett. 73, 1227–1230 (1994).
[3] Y. H. Lai et al. Phys. Rev. A 101, 013405 (2020).
[4] P. B. Corkum. Phys. Rev. Lett.71, 1994–1997 (1993).
[5] G. D. Gillen, M. A. Walker, and L. D. Van Woerkom. Phys. Rev. A 64, 043413 (2001).
[6] A. Zielinski, V.P. Majety, A. Scrinzi, Phys. Rev. A 93, 023406 (2016).
[7] T. Sato et al. Phys. Rev. A 94, 023405 (2016).
[8] F. Lackner et al. Phys. Rev. A 95, 033414 (2017).
