Stanford Advisors

All Publications

  • Free-electron crystals for enhanced X-ray radiation. Light, science & applications Wong, L. W., Shi, X., Karnieli, A., Lim, J., Kumar, S., Carbajo, S., Kaminer, I., Wong, L. J. 2024; 13 (1): 29


    Bremsstrahlung-the spontaneous emission of broadband radiation from free electrons that are deflected by atomic nuclei-contributes to the majority of X-rays emitted from X-ray tubes and used in applications ranging from medical imaging to semiconductor chip inspection. Here, we show that the bremsstrahlung intensity can be enhanced significantly-by more than three orders of magnitude-through shaping the electron wavefunction to periodically overlap with atoms in crystalline materials. Furthermore, we show how to shape the bremsstrahlung X-ray emission pattern into arbitrary angular emission profiles for purposes such as unidirectionality and multi-directionality. Importantly, we find that these enhancements and shaped emission profiles cannot be attributed solely to the spatial overlap between the electron probability distribution and the atomic centers, as predicted by the paraxial and non-recoil theory for free electron light emission. Our work highlights an unprecedented regime of free electron light emission where electron waveshaping provides multi-dimensional control over practical radiation processes like bremsstrahlung. Our results pave the way towards greater versatility in table-top X-ray sources and improved fundamental understanding of quantum electron-light interactions.

    View details for DOI 10.1038/s41377-023-01363-4

    View details for PubMedID 38267427

  • Jaynes-Cummings interaction between low-energy free electrons and cavity photons. Science advances Karnieli, A., Fan, S. 2023; 9 (22): eadh2425


    The Jaynes-Cummings Hamiltonian is at the core of cavity quantum electrodynamics; however, it relies on bound-electron emitters fundamentally limited by the binding Coulomb potential. In this work, we propose theoretically a new approach to realizing the Jaynes-Cummings model using low-energy free electrons coupled to dielectric microcavities and exemplify several quantum technologies made possible by this approach. Using quantum recoil, a large detuning inhibits the emission of multiple consecutive photons, effectively transforming the free electron into a few-level system coupled to the cavity mode. We show that this approach can be used for generation of single photons, photon pairs, and even a quantum SWAP gate between a photon and a free electron, with unity efficiency and high fidelity. Tunable by their kinetic energy, quantum free electrons are inherently versatile emitters with an engineerable emission wavelength. Hence, they pave the way toward new possibilities for quantum interconnects between photonic platforms at disparate spectral regimes.

    View details for DOI 10.1126/sciadv.adh2425

    View details for PubMedID 37256955

  • Quantum sensing of strongly coupled light-matter systems using free electrons. Science advances Karnieli, A., Tsesses, S., Yu, R., Rivera, N., Zhao, Z., Arie, A., Fan, S., Kaminer, I. 2023; 9 (1): eadd2349


    Strong coupling in light-matter systems is a central concept in cavity quantum electrodynamics and is essential for many quantum technologies. Especially in the optical range, full control of highly connected multi-qubit systems necessitates quantum coherent probes with nanometric spatial resolution, which are currently inaccessible. Here, we propose the use of free electrons as high-resolution quantum sensors for strongly coupled light-matter systems. Shaping the free-electron wave packet enables the measurement of the quantum state of the entire hybrid systems. We specifically show how quantum interference of the free-electron wave packet gives rise to a quantum-enhanced sensing protocol for the position and dipole orientation of a subnanometer emitter inside a cavity. Our results showcase the great versatility and applicability of quantum interactions between free electrons and strongly coupled cavities, relying on the unique properties of free electrons as strongly interacting flying qubits with miniscule dimensions.

    View details for DOI 10.1126/sciadv.add2349

    View details for PubMedID 36598994

  • Miniature light-driven nanophotonic electron acceleration and control ADVANCES IN OPTICS AND PHOTONICS Shiloh, R., Schoenenberger, N., Adiv, Y., Ruimy, R., Karnieli, A., Hughes, T., England, R., Leedle, K., Black, D. S., Zhao, Z., Musumeci, P., Byer, R., Arie, A., Kaminer, I., Hommelhoff, P. 2022; 14 (4): 862-930

    View details for DOI 10.1364/AOP.461142

    View details for Web of Science ID 000917420400002