Quantum spectroscopy of optical near fields using low-energy free-electron Rabi oscillations in synthetic energy space
Phys. Rev. A 114, 042202 – Published 5 October, 2026
DOI: https://doi.org/10.1103/535y-v2mv
Abstract
We propose an ultrafast free-electron quantum interferometry, facilitating the detection of local electromagnetic fields and plasmonic polaritons using an isolated “two-level” electron. The two-level electron is constructed in a synthetic energy space through laser modulation in the Bragg regime. This construction allows the π/2-pulse and π-pulse Rabi oscillation of the electron to serve as “beam splitters” and “mirrors” in detecting near fields or polaritons. We compared this two-level electron interferometry with imaging and interferometric techniques using other matter waves. When the coupling near field is quantized, we predict quantum and vacuum Rabi oscillations of the two-level electron, which can be used to investigate quantum statistics of optical excitations and electron-photon entanglement. Recent advancements in laser control of quantum electron wave packets make the experimental detection of free electron Rabi oscillations feasible. Our study may advance the understanding and applications of resonant light-matter interactions between low-energy electrons and quantum optical fields.
