Control of atom-photon interactions with shaped quantum electron wavepackets

Abstract

Photon emission from atoms and free electrons underlie a wealth of fundamental science and technological innovations. We present a regime where atom-photon and electron-photon interactions interfere with each other, resulting in substantial changes in the spontaneous emission rate compared to the sum of each interaction considered in isolation. We highlight the critical role played by quantum electron wavepackets, and how the emission can be tailored via the electron waveshape, as well as the atomic population and coherence. Our findings reveal that atom-photon and electron-photon interactions cannot be considered in isolation even when higher-order contributions involving all three bodies (atom, photon and free electron) are negligible. Our findings pave the way to more precise control over photon emission processes and related diagnostics.

Quantum sensing of strongly coupled light-matter systems using free electrons

“…Our results showcase the great versatility and applicability of quantum interactions between free electrons and strongly coupled light-matter systems, relying on the unique properties of the free electron as a strongly interacting flying qubit with miniscule dimensions. We note that the related, complementary paper of Lim et al (43) was released simultaneously with our work.…”

“…On the other hand, the idea to use free electrons for coherent interactions with bound electrons was only proposed recently (39). This idea spawned substantial interest and follow-up work (39)(40)(41)(42)(43)(44), for example, the proposal to use free electrons for measuring the quantum state of bound-electron systems (40,42). However, no work so far investigated the coherent and simultaneous quantum interaction of a free electron with strongly coupled systems of light and matter.…”

Free-electron-light interactions in nanophotonics

“…20 Some of the above-mentioned applications have been enabled by recent advances in ultrafast electron microscopy, where electron-beam and optical excitation of the sample can be modulated in time down to attosecond pulses, [118][119][120][121] thereby unveiling quantum properties of electron-light interactions. [122][123][124] In particular, in photon-induced near-field electron microscopy [125][126][127] (PINEM), one can probe nearfield non-equilibrium properties of physical systems with un- precedented time and spatial resolution. The recent introduction of nanophotonics in PINEM has enabled the implementation of cavity quantum electrodynamics 22,23 with free electrons, the generation of electron vortex beams, 128 the coherent control of electron beam statistics, 129 electron beam modulation with silicon photonics, 130 coincidence electron-photon detection, 131,132 and strong coupling in the single-photonsingle-electron regime.…”