Towards ultimate temporal and spatial resolutions with ultrafast single-electron diffraction

Ultrafast electron diffraction and microscopy can provide a four-dimensional visualization of atomic motion in space and time, but space charge effects limit the temporal resolution. In contrast to bright pulses with many electrons, single-electron wave packets have no Coulomb repulsion at all and can hence have ultimate characteristics in space and time. This paper discusses our current understanding of single-electron pulse generation, microwave compression, duration and jitter, pulse front distortions, coherence, pulse metrology and diffraction imaging of atomic and eventually electronic motion on the atomic scale. (review article)