{ "meta": { "api_type": "NWO Projects API", "version": "1.0.2", "licence": { "name": "CC0 1.0 Universal", "url": "https://creativecommons.org/publicdomain/zero/1.0", "description": "To the extent possible under law, all copyright and related or neighbouring rights have been waived worldwide to the data made available through this API." }, "documentation": "https://doi.org/10.5281/zenodo.14918287", "release_date": "2025-08-20T00:00:00", "funder": "https://doi.org/10.13039/501100003246", "ror_id": "https://ror.org/04jsz6e67", "date": "2026-11-05T00:00:00", "count": 1, "per_page": 100, "pages": 1, "page": 1 }, "projects": [ { "project_id": "OCENW.KLEIN.488", "title": "Quantum electron wavepacket synthesizer", "funding_scheme_id": 4148, "funding_scheme": "Open Competitie ENW - M Doorlopend OC ENW KLEIN Pakket 08", "department": "Exacte en Natuurwetenschappen", "sub_department": "Exacte en Natuurwetenschappen", "start_date": "2021-10-01T00:00:00", "end_date": "2025-09-30T00:00:00", "reporting_year": 2020, "summary_nl": "High-energy (1-200 keV) electrons are extensively used to study optical materials excitations such as plasmons and other resonant phenomena that have applications in quantum communication, opto-electronics, biosensors, photovoltaics, and more. A key question in these interactions is: when is the electron acting as a classical point charge with the interactions described by classical electrodynamics, and when is the electron wavepacket quantum mechanically entangled with materials excitations? In this project we will design a new instrument to address this question by synthesizing the shape of the electron wavepacket at will. We integrate a 5 keV scanning electron microscope (SEM) with a pulsed laser system that resonantly excites an optical metasurface composed of nanoscale holes in a thin gold film. The strong plasmonic near fields in the holes modify the energy spectrum of an electron wavepacket passing through the holes, creating energy sidebands of which the distribution is controlled by the light intensity in each hole. Each nanohole serves as a electron wave shaping “pixel”, enabling the synthesis of a desired electron wavepacket energy spectrum and hence a tailored temporal and spatial profile.\n\nThe new instrument takes advantage of the high efficiency of the near-field-electron energy exchange at low electron energy (5 keV), and uses a retarding field electron analyser to measure the quantized electron energy spectra. We detect the cathodoluminescence (CL) spectrum, polarization, angular pattern and photon statistics of the generated light for different electron wavepacket energy distributions. We carry out three complementary CL experiments of which the outcome is sensitive to whether the electron acts as a particle or as a wave: (1) the generation of transition radiation at a metal surface, (2) cathodoluminescence holography of resonantly excited surface plasmons, (3) and resonant excitation of NV centers in diamond. The demonstration of synthesized electron wavepackets will open up many applications in the new field of quantum electron microscopy in which electrons are entangled with materials excitations.", "summary_en": "High-energy (1-200 keV) electrons are extensively used to study optical materials excitations such as plasmons and other resonant phenomena that have applications in quantum communication, opto-electronics, biosensors, photovoltaics, and more. A key question in these interactions is: when is the electron acting as a classical point charge with the interactions described by classical electrodynamics, and when is the electron wavepacket quantum mechanically entangled with materials excitations? In this project we will design a new instrument to address this question by synthesizing the shape of the electron wavepacket at will. We integrate a 5 keV scanning electron microscope (SEM) with a pulsed laser system that resonantly excites an optical metasurface composed of nanoscale holes in a thin gold film. The strong plasmonic near fields in the holes modify the energy spectrum of an electron wavepacket passing through the holes, creating energy sidebands of which the distribution is controlled by the light intensity in each hole. Each nanohole serves as a electron wave shaping “pixel”, enabling the synthesis of a desired electron wavepacket energy spectrum and hence a tailored temporal and spatial profile.\n\nThe new instrument takes advantage of the high efficiency of the near-field-electron energy exchange at low electron energy (5 keV), and uses a retarding field electron analyser to measure the quantized electron energy spectra. We detect the cathodoluminescence (CL) spectrum, polarization, angular pattern and photon statistics of the generated light for different electron wavepacket energy distributions. We carry out three complementary CL experiments of which the outcome is sensitive to whether the electron acts as a particle or as a wave: (1) the generation of transition radiation at a metal surface, (2) cathodoluminescence holography of resonantly excited surface plasmons, (3) and resonant excitation of NV centers in diamond. The demonstration of synthesized electron wavepackets will open up many applications in the new field of quantum electron microscopy in which electrons are entangled with materials excitations.", "award_amount": 355770, "grant_id": "https://doi.org/10.61686/BYTIU26894", "project_members": [ { "role": "Researcher", "member_id": 519623, "last_name": "Akerboom", "degree_post_nominal": "MSc", "initials": "E.", "first_name": "Evelijn", "organisation": "NWO-institutenorganisatie||AMOLF", "organisation_id": 49475, "ror": "https://ror.org/038x9td67", "active": false }, { "role": "Main Applicant", "member_id": 174610, "last_name": "Polman", "degree_pre_nominal": "prof. dr.", "initials": "A.", "first_name": "Albert", "organisation": "NWO-institutenorganisatie||AMOLF", "organisation_id": 49475, "ror": "https://ror.org/038x9td67", "active": true }, { "role": "Project leader", "member_id": 174610, "last_name": "Polman", "degree_pre_nominal": "prof. dr.", "initials": "A.", "first_name": "Albert", "organisation": "NWO-institutenorganisatie||AMOLF", "organisation_id": 49475, "ror": "https://ror.org/038x9td67", "active": true } ], "products": [ { "title": "Free Electron–Plasmon Coupling Strength and Near-Field Retrieval through Electron Energy-Dependent Cathodoluminescence Spectroscopy", "year": 2024, "edition": "21", "start": 13560, "end": 13567, "type": "Wetenschappelijk artikel", "url_open_access": "https://www.doi.org/10.1021/acsnano.3c12972", "journal_title": "ACS Nano", "authors": [ { "last_name": "Polman", "initials": "A.", "role": "Auteur" }, { "last_name": "Akerboom", "initials": "E.", "role": "Auteur" }, { "last_name": "García de Abajo", "initials": "F. J.", "role": "Auteur" }, { "last_name": "Schilder", "initials": "N.J.", "role": "Auteur" }, { "last_name": "Di Giulio", "initials": "V.", "role": "Auteur" } ] }, { "title": "Toward Optimum Coupling between Free Electrons and Confined Optical Modes", "year": 2024, "edition": "22", "start": 14255, "end": 14275, "type": "Wetenschappelijk artikel", "url_open_access": "https://www.doi.org/10.1021/acsnano.3c12977", "journal_title": "ACS Nano", "authors": [ { "last_name": "Polman", "initials": "A.", "role": "Auteur" }, { "last_name": "Akerboom", "initials": "E.", "role": "Auteur" }, { "last_name": "García de Abajo", "initials": "F. J.", "role": "Auteur" }, { "last_name": "Di Giulio", "initials": "V.", "role": "Auteur" } ] }, { "title": "Angle-Resolved Cathodoluminescence Interferometry of Plasmonic and Dielectric Scatterers", "year": 2025, "edition": "39", "start": 14264, "end": 14269, "type": "Wetenschappelijk artikel", "url_open_access": "https://www.doi.org/10.1021/acs.nanolett.5c02952", "journal_title": "Nano Letters", "authors": [ { "last_name": "Polman", "initials": "A.", "role": "Auteur" }, { "last_name": "Akerboom", "initials": "E.", "role": "Auteur" }, { "last_name": "García de Abajo", "initials": "F.J.", "role": "Auteur" }, { "last_name": "Sugimoto", "initials": "H.", "role": "Auteur" }, { "last_name": "Fujii", "initials": "M.", "role": "Auteur" } ] }, { "title": "Electron-Energy Dependent Excitation and Directional Far-Field Radiation of Resonant Mie Modes in Single Si Nanospheres", "year": 2025, "edition": "8", "start": 4161, "end": 4170, "type": "Wetenschappelijk artikel", "url_open_access": "https://www.doi.org/10.1021/acsphotonics.5c00173", "journal_title": "ACS Photonics", "authors": [ { "last_name": "Polman", "initials": "A.", "role": "Auteur" }, { "last_name": "Akerboom", "initials": "E.", "role": "Auteur" }, { "last_name": "Sugimoto", "initials": "H.", "role": "Auteur" }, { "last_name": "Fujii", "initials": "M.", "role": "Auteur" }, { "last_name": "Stamatopoulou", "initials": "P.E.", "role": "Auteur" }, { "last_name": "Fiedler", "initials": "S.", "role": "Auteur" }, { "last_name": "Soler", "initials": "T.", "role": "Auteur" } ] } ] } ] }