  Two-dimensional systems can host exotic particles called anyons whose quantum
statistics are neither bosonic nor fermionic. For example, the elementary
excitations of the fractional quantum Hall effect at filling factor $\nu=1/m$
(where m is an odd integer) have been predicted to obey abelian fractional
statistics, with a phase $\varphi$ associated with the exchange of two
particles equal to $\pi/m$. However, despite numerous experimental attempts,
clear signatures of fractional statistics remain elusive. Here we
experimentally demonstrate abelian fractional statistics at filling factor
$\nu=1/3$ by measuring the current correlations resulting from the collision
between anyons at a beam-splitter. By analyzing their dependence on the anyon
current impinging on the splitter and comparing with recent theoretical models,
we extract $\varphi=\pi/3$, in agreement with predictions.
