  Coulomb interaction has a striking effect on electronic propagation in one
dimensional conductors. The interaction of an elementary excitation with
neighboring conductors favors the emergence of collective modes which
eventually leads to the destruction of the Landau quasiparticle. In this
process, an injected electron tends to fractionalize into separated pulses
carrying a fraction of the electron charge. Here we use two-particle
interferences in the electronic analog of the Hong-Ou-Mandel experiment in a
quantum Hall conductor at filling factor 2 to probe the fate of a single
electron emitted in the outer edge channel and interacting with the inner one.
By studying both channels, we analyze the propagation of the single electron
and the generation of interaction induced collective excitations in the inner
channel. These complementary information reveal the fractionalization process
in time domain and establish its relevance for the destruction of the
quasiparticle which degrades into the collective modes.
