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Quantum computing and quantum optics with recoiled free electrons

Maxim Sirotin1,2,3,4,*, Andrei Rasputnyi1,2,†, Tomáš Chlouba1,‡, Roy Shiloh1,5,§, and Peter Hommelhoff1,6,∥

  • *Contact author: msirotin@g.harvard.edu
  • †Contact author: andrei.rasputnyi@mpl.mpg.de
  • ‡Contact author: chloubatom@gmail.com
  • §Contact author: roy.shiloh@mail.huji.ac.il
  • ∥Contact author: peter.hommelhoff@fau.de
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Phys. Rev. Research 8, 043123 – Published 2 November, 2026

DOI: https://doi.org/10.1103/4rv2-8jxw

Abstract

Coherent interactions between free electrons and optical fields offer a promising route to quantum control, nonclassical state generation, and programmable quantum dynamics. At kiloelectron-volt electron energies, the emission or absorption of optical photons produces appreciable quantum recoil, resolving the electron into a discrete and controllable energy ladder. Starting from relativistic quantum electrodynamics, we derive an exact recoil-resolved interaction Hamiltonian in a traveling-wave picture. The resulting recoil ladder forms a high-dimensional qudit with programmable couplings and sufficient controllability for universal quantum computation. We demonstrate its use for analog quantum simulation, including one-dimensional curved-spacetime models and synthetic black-hole horizons, as well as for quantum information processing, where multiple logical qubits and high-fidelity gates can be realized within a single electron. In parallel, the same recoil-enabled dynamics allow the controlled creation of complex hybrid electron-photon states, in which engineered ladder transitions imprint nonclassical correlations and structure onto the emitted light. Together, these results establish recoiled free electrons as a versatile platform bridging quantum optics, quantum control, Hamiltonian engineering, quantum simulation, and quantum information processing.

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Phys. Rev. Research 8, 043123– Published 2 November, 2026
  • Received 21 May 2026
  • Accepted 9 October 2026
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