  We present a novel method to measure the arrival time statistics of
continuous electron beams with sub-ps resolution, based on the combination of
an RF deflection cavity and fast single electron imaging. We observe Poissonian
statistics within time bins from 100~ns to 2~ns and increasingly pronounced
sub-Poissonian statistics as the time bin decreases from 2~ps to 340~fs. This
2D streak-camera in principle enables femtosecond-level arrival time
measurements, paving the way to observing Pauli blocking effects in electron
beams and thus serving as an essential diagnostic tool towards degenerate
electron beam sources for free electron quantum optics.
