We show that the coherent interaction between free electrons and photons can be used for universal control of continuous-variable photonic quantum states in the form of Gottesman-Kitaev-Preskill (GKP) qubits. Specifically, we find that electron energy combs enable non-destructive measurements of the photonic state and can induce arbitrary gates. Moreover, a single electron interacting with multiple photonic modes can create highly entangled states such as Greenberger-Horne-Zeilinger states and cluster states of GKPs.
@article{arxiv.2303.13244,
title = {Free-electron interactions with photonic GKP states: universal control and quantum error correction},
author = {Gefen Baranes and Shiran Even-Haim and Ron Ruimy and Alexey Gorlach and Raphael Dahan and Asaf A. Diringer and Shay Hacohen-Gourgy and Ido Kaminer},
journal= {arXiv preprint arXiv:2303.13244},
year = {2026}
}