  Using a periodic train of Lorentzian voltage pulses, which generates
soliton-like electronic excitations called Levitons, we investigate the charge
density backscattered off a quantum point contact in the fractional quantum
Hall regime. We find a regular pattern of peaks and valleys, reminiscent of
analogous self-organization recently observed for optical solitons in
non-linear environments. This crystallization phenomenon is confirmed by
additional side dips in the Hong-Ou-Mandel noise, a feature that can be
observed in nowadays electron quantum optics experiments.
