  The one-dimensional, chiral edge channels of the quantum Hall effect are a
promising platform in which to implement electron quantum optics experiments;
however, Coulomb interactions between edge channels are a major source of
decoherence and energy relaxation. It is therefore of large interest to
understand the range and limitations of the simple quantum electron optics
picture. Here we confirm experimentally for the first time the predicted
relaxation and revival of electrons injected at finite energy into an edge
channel. The observed decay of the injected electrons is reproduced
theoretically within a Tomonaga-Luttinger liquid framework, including an
important dissipation towards external degrees of freedom. This gives us a
quantitative empirical understanding of the strength of the interaction and the
dissipation.
