Pairwise quantum correlations in four-level quantum dot systems

TL;DR

This paper investigates how Coulomb interaction and temperature affect pairwise quantum entanglement, coherence, and correlations in four-level quantum dot systems modeled as quadrit-quadrit states, revealing entanglement's resilience to temperature with stronger Coulomb interaction.

Contribution

It introduces a model of quantum dots as quadrit-quadrit systems and analyzes the impact of Coulomb interaction and temperature on quantum correlations, providing new insights into their behavior.

Findings

Entanglement is more resistant to temperature increases with stronger Coulomb interaction.

Quantum correlations can be explained through energy spectrum features like ground state degeneracy.

The study models quantum dots beyond simple qubit systems, using a four-level approach.

Abstract

In this paper we assume quantum dots can be assimilated to Fermi Hubbard sites when the Coulomb interaction between electrons is higher compared to their tunneling. The study of pairwise entanglement in a small size array of quantum dots allows to model each pair as a quadrit-quadrit system (4 $\times$ 4 mixed state) instead of the more common and simplistic approach of describing it in quantum information as a qubit-qubit system. We study the effect of Coulomb interaction and temperature on pairwise entanglement as well as on quantum coherence and total correlations. The crucial results of this study are that entanglement resists better the increase in temperature when the Coulomb interaction is stronger. Moreover, we successfully explain the behavior of these correlations in terms of the energy spectrum, namely the ground state degeneracy and the state energy difference.