邀请人：李建奇研究员 杨槐馨研究员

联系人：孙帅帅副研究员（82649180）

报告摘要：

Free electrons provide a unique platform for exploring quantum interactions between matter and light, and electron microscopy offers a powerful setting in which these interactions can be controlled and detected. In this talk, I will discuss two complementary regimes of free-electron-photon quantum coupling: elastic dispersive interaction and inelastic nonlinear SU(1,1) interaction. First, I will introduce a quantum-optical framework for elastic electron-photon coupling, in which a passing electron induces a phase shift on a photonic mode while its own quantum state is preserved. This electron-induced "phase kickback" can be described as a dispersive interaction, or equivalently as an effective refractive index of a free electron. The accumulated optical phase is proportional to the number of electrons, suggesting a route toward quantum non-demolition electron counting and quantum-enhanced electron imaging. I will then discuss a distinct nonlinear regime in which a free electron interacts with the photonic vacuum through two-photon processes. The resulting scattering operator follows the SU(1,1) algebra and enables electron-induced vacuum squeezing and two-mode squeezed-vacuum states, allowing a free electron to generate correlated photon pairs without an external optical pump. Together, these results establish free electrons as both quantum probes of photonic fields and active sources of nonclassical light, opening new possibilities at the interface of electron microscopy, quantum optics, and photonics.

[1] Dingguo Zheng and Ofer Kfir, Elastic quantum coupling between free electrons and photons. Sci. Adv. 12,eaed3278 (2026).

[2] Dingguo Zheng and Ofer Kfir, SU(1,1) interactions of free electrons with the photonic vacuum. In preparation.

报告人简介:

Dingguo Zheng is currently a Postdoctoral Researcher at Tel Aviv University. He received his PhD in 2022 from the Institute of Physics, Chinese Academy of Sciences, under the supervision of Prof. Jianqi Li, where he focused on the experimental study of the interaction between free electrons and optical near fields. Since 2023, he has conducted theoretical research on quantum free-electron–photon interactions with Prof. Ofer Kfir. His research focuses on ultrafast electron microscopy, spanning ultrafast electron diffraction and spectroscopy, photon-induced near-field electron microscopy. He has published twenty papers in journals such as Nat. Commun., Sci. Adv., Nano Lett. and Laser & Photonics Reviews.