Tunneling of Hybridized Pairs of Electrons through a One-Dimensional Channel

TL;DR

This paper models quantum ballistic transport of electrons in a short 1D channel, highlighting how Coulomb interactions cause energy level splitting and state switching, affecting conductance in low-temperature regimes.

Contribution

It introduces a physical model for two-electron states in a quasi-1D channel, revealing Coulomb-induced energy level splitting and state switching phenomena.

Findings

Coulomb interaction causes four split energy levels in two-electron states.

The ground state switches between anti-crossing and crossing states as channel width varies.

Ballistic conductance is influenced by many-body effects despite fixed center-of-mass velocity.

Abstract

Recently, the electron transport through a quasi-one dimensional (quasi-1D) electron gas was investigated experimentally as a function of the confining potential. We present a physical model for quantum ballistic transport of electrons through a short conduction channel, and investigate the role played by the Coulomb interaction in modifying the energy levels of two-electron states at low temperatures as the width of the channel is increased. In this regime, the effect of the Coulomb interaction on the two-electron states has been shown to lead to four split energy levels, including two anti-crossings and two crossing-level states. Due to the interplay between the anti-crossing and crossing of the energy levels, the ground state for the two-electron model switches from one anti-crossing state for strong confinement to a crossing state for intermediate confinement as the channel width is first increased, and then returned to its original anti-crossing state. This switching behavior is related to the triplet spin degeneracy as well as the Coulomb repulsion and reflected in the ballistic conductance. Here, many-body effects can still affect electron occupations in the calculation of quantum ballistic conductance although it cannot vary the center-of-mass velocity.