Trapped electrons in the quantum degenerate regime

TL;DR

This paper investigates the quantum behavior of trapped electron pairs in a harmonic potential, analyzing energy spectra across different coupling regimes to inform many-electron system models.

Contribution

It provides a detailed analysis of the energy spectrum of a trapped electron pair with Coulomb interaction, extending previous work and exploring regimes relevant for many-electron systems.

Findings

Eigenenergy of the ground state confirmed and extended.

Complete set of scaled energies for all trapping strengths provided.

Perturbative methods are effective in both strong and weak coupling regimes.

Abstract

A full strength Coulomb interaction between trapped electrons can be felt only in absence of a neutralizing background. In order to study quantum degenerate electrons without such a background, an external trap is needed to compensate for the strong electronic repulsion. As a basic model for such a system, we study a trapped electron pair in a harmonic trap with an explicit inclusion of its Coulomb interaction. We find the eigenenergy of the ground state, confirming earlier work in the context of harmonium. We extend this to a complete set of properly scaled energies for any value of the trapping strength, including the excited states. The problem is solved either numerically or by making harmonic approximations to the potential. As function of the trapping strength a crossover can be made from the strongly to the weakly-coupled regime, and we show that in both regimes perturbative methods based on a pair-wise electron description would be effective for a many-particle trapped electron system, which resembles a Wigner crystal in the ground state of the strongly coupled limit.