Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice

TL;DR

This paper reports the creation of a tunable two-dimensional electron system in a honeycomb lattice, revealing collective excitations and a potential new Coulomb-driven ground state, advancing quantum simulation in solid-state platforms.

Contribution

It demonstrates the trapping of electrons in an artificial honeycomb lattice and probes their collective excitations, providing experimental insights into the Mott-Hubbard model in a solid-state system.

Findings

Identification of novel collective modes in a magnetic field

Determination of the Hubbard gap in the artificial lattice

Evidence suggesting a Coulomb-driven ground state

Abstract

Electrons in artificial lattices enable explorations of the impact of repulsive Coulomb interactions in a tunable system. We have trapped two-dimensional electrons belonging to a gallium arsenide quantum well in a nanofabricated lattice with honeycomb geometry. We probe the excitation spectrum in a magnetic field identifying novel collective modes that emerge from the Coulomb interaction in the artificial lattice as predicted by the Mott-Hubbard model. These observations allow us to determine the Hubbard gap and suggest the existence of a novel Coulomb-driven ground state. This approach offers new venues for the study of quantum phenomena in a controllable solid-state system.