Imaging the Wigner Crystal of Electrons in One Dimension

TL;DR

This paper reports the first direct imaging of the elusive one-dimensional Wigner crystal of electrons, using a minimally invasive scanning probe technique with carbon nanotubes to visualize electron ordering in real space.

Contribution

It introduces a novel scanning method employing a pristine carbon nanotube to image fragile many-electron states with minimal perturbation, enabling direct observation of the Wigner crystal.

Findings

Electrons form a pearl-like ordered structure in one dimension.

Coulomb interactions dominate over kinetic energy in the observed state.

The experimental images match theoretical models of strongly interacting electrons.

Abstract

The quantum crystal of electrons, predicted more than eighty years ago by Eugene Wigner, is still one of the most elusive states of matter. Here, we present experiments that observe the one-dimensional Wigner crystal directly, by imaging its charge density in real-space. To measure this fragile state without perturbing it, we developed a new scanning probe platform that utilizes a pristine carbon nanotube as a scanning charge perturbation to image, with minimal invasiveness, the many-body electronic density within another nanotube. The obtained images, of few electrons confined in one-dimension, match those of strongly interacting crystals, with electrons ordered like pearls on a necklace. Comparison to theoretical modeling demonstrates the dominance of Coulomb interactions over kinetic energy and the weakness of exchange interactions. Our experiments provide direct evidence for this long-sought electronic state, and open the way for studying other fragile interacting states by imaging their many-body density in real-space.