Nonlinear dynamics of electron-positron clusters

TL;DR

This paper models electron-positron clusters using quantum hydrodynamics, analyzing their static, linear, and nonlinear behaviors, and demonstrates efficient population separation via autoresonant laser pulses.

Contribution

It introduces a quantum hydrodynamic approach to study electron-positron clusters, validating static features and exploring nonlinear dynamics with laser-induced separation.

Findings

Static features match Hartree-Fock calculations

Dipole mode resembles surface plasmon in metals

Autoresonant laser pulses can separate populations in femtoseconds

Abstract

Electron-positron clusters are studied using a quantum hydrodynamic model that includes Coulomb and exchange interactions. A variational Lagrangian method is used to determine their stationary and dynamical properties. The cluster static features are validated against existing Hartree-Fock calculations. In the linear response regime, we investigate both dipole and monopole (breathing) modes. The dipole mode is reminiscent of the surface plasmon mode usually observed in metal clusters. The nonlinear regime is explored by means of numerical simulations. We show that, by exciting the cluster with a chirped laser pulse with slowly varying frequency (autoresonance), it is possible to efficiently separate the electron and positron populations on a timescale of a few tens of femtoseconds.