Arbitrarily shaped high-coherence electron bunches from ultracold plasma*

Sources of inherently cold electrons extracted from laser cooled atoms have the potential to transform electron imaging. These sources promise both the spatial coherence and high current required for picosecond molecular scale imaging. Here we demonstrate arbitrary and real-time control of electron bunch shape and thus realise a major step towards alleviation of electron source brightness limitations due to Coulomb explosion. The ability to dynamically shape the electron source itself and to observe that pattern in the propagated electron bunch provides a remarkable experimental demonstration of the intrinsically high spatial coherence of a cold electron source.