Droplets of three electrons behave like a liquid

Electrons repel each other strongly through the Coulomb interaction, which acts between all charged particles. In a system of many electrons, these interactions can create a liquid-like phase, called a Coulomb liquid. In a paper in Nature, Shaju et al.¹ bridge the gap between the Coulomb interactions in single pairs of electrons and the emergence of the Coulomb liquid, finding evidence that a ‘droplet’ of just three electrons shows the characteristics of a Coulomb liquid. The behaviour of a Coulomb liquid is characterized by strong interparticle interactions. This means that the motions of the electrons are correlated — what one electron does depends on what the others are doing. Shaju et al. studied the emergence of the Coulomb liquid in objects called electron droplets, which comprise small numbers (in this work, between two and five) of interacting electrons confined in a small space. The researchers’ approach was to split an electron droplet in two and to measure the correlations between the electrons in the resulting smaller droplet.