Evidence of Coulomb liquid phase in a few-electron droplets

In physics, correlations in fluctuating microscopic observables can provide key information about collective states of matter, such as the quark-gluon plasma formed in heavy-ion collisions (Science 332, 1525, 2011) or expanding quantum degenerate gases (Science 296, 1703, 1999). Mesoscopic colliders, through shot-noise measurements, have provided smoking-gun evidence on the nature of exotic electronic excitations such as fractional charges, levitons and anyon statistics. Yet, bridging the gap between two-particle collisions and the emergence of collectivity as the number of interacting particles increases remains a challenging task at the microscopic level.

 In this presentation we demonstrate all-body correlations in the partitioning of electron droplets containing up to 5 electrons, driven by a moving potential well through a Y-junction in a semiconductor device. Analyzing the partitioning data using high-order multivariate cumulants and finite-size scaling towards the thermodynamic limit reveals distinctive fingerprints of a strongly-correlated Coulomb liquid  (Nature 642, 928, 2025) . These fingerprints agree well with a universal limit where the partitioning of a droplet is predicted by a single collective variable. Our electron-droplet collider reveals the intricate interplay between confinement and interaction effects in few-electron systems, establishing a novel approach to probe engineered states of matter. This platform opens new avenues to study strongly correlated and coherent many-body phenomena in mesoscopic systems.