Ultrafast Two-electron Orbital Swap in Li Initiated by Attosecond pulses

TL;DR

This paper reports the discovery of a universal ultrafast two-electron orbital swap mechanism in lithium, initiated by attosecond pulses, which enables control over spin polarization in photoelectron pairs through quantum beats.

Contribution

It introduces a novel quantum beat mechanism causing two-electron orbital swaps in lithium, enabling ultrafast manipulation of spin-resolved electron dynamics.

Findings

Orbital swap occurs within several hundred attoseconds.

Spin polarization of photoelectrons can be manipulated.

Mechanism is initiated by two-photon double ionization of Li.

Abstract

A universal mechanism of ultrafast two-electron orbital swap is discovered through two-photon sequential double ionization of Li. After a $1s$ electron in Li is ionized by absorbing an EUV photon, the other two bound electrons located on two different shells have either parallel or antiparallel spin orientations. In the latter case, these two electrons are in the superposition of the singlet and triplet states with different energies, forming a quantum beat and giving rise to the two-electron orbital swap with a period of several hundred attoseconds. The orbital swap mechanism can be used to manipulate the spin polarization of photoelectron pairs by conceiving the attosecond-pump attosecond-probe strategy, and thus serves as a knob to control spin-resolved multielectron ultrafast dynamics.