  In this report we review the present state of the art of the control of
propagating quantum states at the single-electron level and its potential
application to quantum information processing. We give an overview of the
different approaches which have been developed over the last ten years in order
to gain full control over a propagating single electron in a solid state
system. After a brief introduction of the basic concepts, we present
experiments on flying qubit circuits for ensemble of electrons measured in the
low frequency (DC) limit. We then present the basic ingredients necessary to
realise such experiments at the single-electron level. This includes a review
of the various single electron sources which are compatible with integrated
single electron circuits. This is followed by a review of recent key
experiments on electron quantum optics with single electrons. Finally we will
present recent developments about the new physics that emerges using ultrashort
voltage pulses. We conclude our review with an outlook and future challenges in
the field.
