3D correlations and the simplest sub-shot-noise ultrafast electron source

López Hoffmann F, Meier S, Heimerl J, Knipfer M, Volk T, Hommelhoff P (2026)

Publication Type: Conference contribution

Publication year: 2026

Publisher: Institute of Electrical and Electronics Engineers Inc.

Conference Proceedings Title: 2026 39th International Vacuum Nanoelectronics Conference, IVNC 2026

Event location: Tokyo

ISBN: 9798331564360

DOI: 10.1109/IVNC69421.2026.11660917

Abstract

Correlations between ultrafast free electrons emitted from nanometric sources strongly influence electron beam formation and quality. When several electrons are emitted within nanometric volumes and femtosecond timescales, Coulomb interactions redistribute phase space longitudinally and transversely, thereby affecting energy spread, focusability, and brightness. At the same time, such correlations can be harnessed to prepare non-Poissonian beams: Earlier work established pronounced longitudinal energy anticorrelations for ultrafast emission from bare needle tips [1] and in strongly filtered electron microscope geometries [2]. Here we address the full three-dimensional behavior by resolving both energetic and spatial correlations of two-electron events emitted from a sharp tungsten needle tip. A key enabling element is an improved deep-learning-based multi-hit reconstruction for delay-line detectors, which substantially enhances the reliable recovery of near-coincident events [3]. The measurements reveal a continuous trade-off between longitudinal and transverse Coulomb repulsion: small mutual angles coincide with pronounced energetic separation, whereas events with small energy difference exhibit strong spatial avoidance. This also shows that an ordinary aperture, already present in most electron-beam setups, can act as an effective correlation filter and provide a particularly simple route toward sub-shot-noise ultrafast electron beams. Comparison with semiclassical particle simulations indicates that temporal confinement primarily governs the longitudinal energy splitting, whereas source geometry strongly influences the transverse repulsion.

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How to cite

APA:

López Hoffmann, F., Meier, S., Heimerl, J., Knipfer, M., Volk, T., & Hommelhoff, P. (2026). 3D correlations and the simplest sub-shot-noise ultrafast electron source. In 2026 39th International Vacuum Nanoelectronics Conference, IVNC 2026. Tokyo, JP: Institute of Electrical and Electronics Engineers Inc..

MLA:

López Hoffmann, Felix, et al. "3D correlations and the simplest sub-shot-noise ultrafast electron source." Proceedings of the 39th International Vacuum Nanoelectronics Conference, IVNC 2026, Tokyo Institute of Electrical and Electronics Engineers Inc., 2026.

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