  We study the time-dependent dynamical phase of fractional quasiparticles in
quantum Hall states using Ramsey interferometry. A Ramsey two-pulse voltage
modulation generates an interference term in the current noise of a quantum
point contact oscillating with the dynamical phase. We show that the
interference pattern probes the Green's function of the fractional
quasi-particles in the time domain and reveals the fractional charge. We
address both the case of a point-like tunnel junction and the case of
momentum-resolved tunneling which also provides information on the speed of
those quasiparticles propagating along the edge. For the 5/2 fractional quantum
Hall case, the Ramsey signal can differentiate between the Pfaffian and
anti-Pfaffian states.
