Chin. Phys. B, 2021, Vol. 30(2): 024203    DOI: 10.1088/1674-1056/abb7fb
 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS Prev   Next

Effects of initial electronic state on vortex patterns in counter-rotating circularly polarized attosecond pulses

Qi Zhen(甄琪), Jia-He Chen(陈佳贺), Si-Qi Zhang(张思琪), Zhi-Jie Yang(杨志杰), and Xue-Shen Liu(刘学深)†
Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
Abstract  We theoretically investigate the effects of different electronic states as the initial state on the vortex patterns in photoelectron momentum distributions (PMDs) from numerical solutions of the two-dimensional (2D) time-dependent Schrödinger equation (TDSE) of $$\rmHe^+$$ with a pair of counter-rotating circularly polarized attosecond pulses. It is found that the number of spiral arms in vortex patterns is equal to the number of the absorbed photons when the initial state is the ground state. However, the number of spiral arms in vortex patterns is always two more than the number of the absorbed photons when the initial state is the excited state. This sensitivity is attributed to the initial electron density distribution. In addition, we have demonstrated the PMDs for different initial electronic states with the same wavelengths and analyzed their corresponding physical mechanisms. It is illustrated that the method presented can be employed to effectively control the distribution of the electron vortices.
Keywords:  initial electronic state      counter-rotating circularly polarized attosecond pulses      vortex patterns      photoelectron momentum distributions
Received:  11 August 2020      Revised:  01 September 2020      Accepted manuscript online:  14 September 2020
 PACS: 42.50.Hz (Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift) 42.65.Ky (Frequency conversion; harmonic generation, including higher-order harmonic generation) 32.80.Rm (Multiphoton ionization and excitation to highly excited states)
Fund: Project supported by the National Natural Science Foundation of China (Grant No. 12074142), the Natural Science Foundation of Jilin Province of China (Grant No. 20180101225JC), and the Graduate Innovation Fund of Jilin University, China (Grant No. 101832020CX337).
Corresponding Authors:  Corresponding author. E-mail: liuxs@jlu.edu.cn