"These on-chip devices accelerate sub-relativistic electrons of initial energy 83.4 keV by 1.21 keV over 30 μm, providing peak acceleration gradients of 40.3 Me

"These on-chip devices accelerate sub-relativistic electrons of initial energy 83.4 keV by 1.21 keV over 30 μm, providing peak acceleration gradients of 40.3 MeV/m." (Sapra et al. Science 2020) Lasers on a chip plus photonic waveguide technology, oh my! https://arxiv.org/pdf/1905.12822 https://arxiv.org/pdf/1905.12822 [edit this is an earlier version see other comment]