Single anyons and anyon binding in a quantum Hall dot

Abstract

Anyons are particles with quantized fractional statistics. In theory, a single anyon can be stabilized as a localized fractional charge within the bulk of a topologically ordered two-dimensional insulator. However, experiments to date have focused on probing anyons in structures in which many anyonic excitations coexist and interact. Here, we demonstrate the trapping of a single anyon in a device consisting of a graphene-based quantum point contact with an embedded tunable quantum Hall dot. Benchmarking our device at v = 1, we demonstrate backscattering between Fermi liquid edge states mediated by the whole-electron Coulomb blockade of the dot. The cleanliness and control available in our device allow depletion of the dot to the last quasihole, and we observe spin blockade for transitions to the opposite-spin Landau level. At v = 1/3 and 2/3, we observe backscattering resonances with three times the frequency, consistent with resonant transmission of e/3 charges via a single anyon transistor. We demonstrate controlled depletion to the last quasiparticle to form a single anyon quantum dot. Tracing the charge addition spectrum for quasiparticle number Nqp = 1-5, we observe highly irregular addition energies, consistent with DMRG modeling showing a complex orbital shell-filling behavior. At higher Nqp = 10-20, the addition energies show a striking pattern: quasiholes at 1/3 (and quasiparticles at 2/3) show a regular addition spectrum while quasiparticles at 1/3 (and quasiholes at 2/3) do not. We trace the origin of this irregularity to an attractive component of the inter-anyon interaction: by experimentally tuning the confining energy, we observe complete suppression of alternating charge sectors, after which the dot charges in increments of twice the fundamental charge. This observation indicates the emergence of an anyon binding energy as large as the charging energy.