Bilayer excitons in the Laughlin fractional quantum Hall state

The Laughlin state provides a description for a universal class of fractional quantum Hall effects that arise in two-dimensional electron systems subjected to strong perpendicular magnetic fields. Conventionally described by a single-component wavefunction, the Laughlin state features fractionally charged quasiparticles that result from correlations within one electronic layer. Here we explore a bilayer situation with interlayer Coulomb coupling between two intralayer Laughlin states that creates excitons between them in a quantum Hall graphene structure. Although quasiparticle excitations typically exhibit charge gaps of tens of kelvins, we observe that this energy scale is lowered through interlayer excitonic pairing between quasiparticles and quasiholes. We identify these excitons in our transport measurements and show that they belong to a category of charge-neutral anyons, thus opening an avenue for investigating exotic quantum statistics and phases of matter. Laughlin states are descriptions of the quantum Hall effect in which interactions between electrons create fractionally charged quasiparticles. Now, excitons are shown to form between these quasiparticles in a bilayer graphene device.