Speaker
Description
The interaction between light and free electrons not only provides a promising pathway toward the miniaturization of electron accelerators, but also enables rich quantum effects that can drive frontier applications such as quantum sensing and quantum light sources with high spatial and temporal resolution. This talk will include the following 3 aspects of free-electron—light interaction:
(1) Nanophotonic electron accelerators. Electron accelerators are important in studying fundamental science, research, medical diagnosis and treatment, and industrial processing. In dielectric laser accelerators (DLAs), laser pulses interact with electron beams in the vicinity of dielectric nanostructures and can provide acceleration gradients more than one order of magnitude higher than conventional radio-frequency accelerators. One key challenge of DLAs is the low current throughput. To increase the DLA current throughput for science and medical applications, we introduced a photonic crystal DLA that has multiple electron channels. Through engineering the band structure of the underlying photonic crystal, we can make the acceleration field in different channels to be almost identical. The photonic crystal DLAs can increase the current throughput by orders of magnitude.
(2) Modulation of free electrons with light. We show that free-space optical modulation of electron pulses can achieve either energy monochromatization or temporal compression, which provides a simple approach to improve the energy and time resolution in ultrafast electron microscopy. Moreover, we show that free-space optical modulation with two counter-propagating Gaussian beams can generate atto-second electron pulse trains with high degree of coherence, where the Gouy phases play a crucial role.
(3) Quantum free-electron—light interaction. Toward the crucial question: what is new in the free-electron—matter interaction with wave-function engineered free electrons, we found out how resonant modulation of the free electron can enhance the interaction between the free electron and a two-level atom and probe the atomic coherence. We also found that distant identical atoms can be entangled by interacting with the same free electron. Moreover, a large coupling between free electrons and photons is generally desired for many free-electron quantum optics applications. We derived an upper bound for the coupling coefficient describing the free-electron—photo interaction. It can provide guidance to reach the strong coupling between free electrons and photons.