The role of final state correlation in double ionization of helium: a master equation approach

TL;DR

This paper investigates the role of final state electron correlation in helium's double ionization by comparing a time-dependent Schrödinger equation approach with a Lindblad equation-based method, demonstrating their agreement in calculating ionization probabilities.

Contribution

It introduces a generalized absorbing boundary approach using the Lindblad equation for systems with multiple particles, validating projection methods for total cross section calculations.

Findings

Both methods agree on double ionization probabilities.

Projection onto uncorrelated states is effective for total cross section estimation.

The Lindblad approach successfully models multi-particle absorption processes.

Abstract

The process of nonsequential two-photon double ionization of helium is studied by two complementary numerical approaches. First, the time-dependent Schr{\"o}dinger equation is solved and the final wave function is analyzed in terms of projection onto eigenstates of the uncorrelated Hamiltonian, i.e., with no electron-electron interaction included in the final states. Then, the double ionization probability is found by means of a recently developed approach in which the concept of absorbing boundaries has been generalized to apply to systems consisting of more than one particle. This generalization is achieved through the Lindblad equation. A model of reduced dimensionality, which describes the process at a qualitative level, has been used. The agreement between the methods provides a strong indication that procedures using projections onto uncorrelated continuum states are adequate when extracting total cross sections for the direct double ionization process.