Refaire sa vie en Bulgarie n'est pas évident pour les Russes qui ont quitté leur pays pour fuir les répressions du régime de Vladimir Poutine. Ils sont confrontés à la réalité parallèle dans laquelle semblent évoluer les autorités bulgares chargées des demandes d'asile.
- Articles / Courrier des Balkans, Société, Une - Diaporama, Bulgarie, UkraineWritten by António Vale with Paul Anton Albrecht.
Lasers have a wide range of current applications, in manufacturing, medicine or communications. Their characteristics vary across different fields and they remain under continuous development, with the academic sector pushing the limits of the technology. One field of interest is laser pulse time acontrol and questions about the shortest processes in nature. These ultrashort processes govern our lives and happen all around us: biological processes are driven by protein folding and enzymatic reactions, the movements of molecules and bond breaking create chemical reactions, and the interaction with light leads to different radiation processes. Most of these can be observed in the ‘femtosecond’ regime. One femtosecond is 10‑15 seconds – if a second was as long as the distance from earth to the sun, we would measure at the scale of a hairs’ width – which would be a single femtosecond.
Huge progress has been made in observing this timescale with ultrashort pulses of light, creating snapshots, or even movies of hitherto unseen processes. The light sources behind such discoveries are often particle accelerators such as synchrotrons or newer XFELs. The latter are very long accelerators that are used to bring free electrons close to the speed of light; these then undulate as they go through an array of magnets, causing them to emit, high-energy light pulses in the form of X-rays. Some of these state-of-the-art facilities are European, such as the European XFEL (EuXFEL, which opened at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg in 2017). XFEL is 3.4 km long and incorporates superconducting accelerator technology. This is a key example of European cooperation hosting a world-leading science centre and connecting scientists across nationalities and disciplines.
Future development could lead to interesting possibilities: chemical reactions and the movement of molecules are still much slower than the electronic processes underlying them – their natural timescale is in the attosecond range (a thousandth of a femtosecond – 10-18s). If we return to our metaphor of a second being equal to the distance of the earth to the sun, we are now considering an entity the size of a microscopic virus. This timescale can be reached with methods such as high-harmonic generation (HHG), which led to Agostini, Krausz and L’Huillier’s award of the 2023 Nobel prize for physics for their work on methods to resolve electron dynamics. However, these are limited to lower intensity pulses, achieving this timescale only at ‘small scale’ (tabletop) and under technical compromises. Theoretical studies on these timescales continue, but experimental limits make a direct comparison quite difficult.
Potential impacts and developmentsThe idea behind investigating any dynamic is most often to make a video of the action. For extremely fast processes, this becomes very difficult, as it is like repeated stop-motion photography using a long-exposure camera and imperfect timing. An investigation is therefore significantly easier with improved camera timing.
To reach the attosecond scale, with high-intensity, high-quality light pulses, several new technological ideas exist, which promise to improve XFELs. These include wakefield acceleration, which accelerates the electrons initially with an additional laser or plasma, reaching high speeds at short length, and technologies that improve the properties and intensity of the resulting laser, such as self-/laser-seeding or enhanced self-amplified spontaneous emission (ESASE). These are already partially implemented in existing and new facilities, such as the Chinese SHINE facility (expected to open in 2026), or the Compact XFEL being built in the United States. Europe relies on existing facilities and established strengths, with plans to improve and upgrade them including an improved electron beam at DESY.
Combining several of these next-generation technologies may allow science to attain the ambitious goal of achieving a reliable resolution of significantly below 100 attoseconds, which could compete with HHG. This would be enough, for example, to precisely track the steps of an electron within a molecule, giving us insight into electronic movements and transitions. This could allow scientists to observe the key steps in light absorption and conversion, charge migration, or chemical reactions. Better understanding of these processes could unlock a range of scientific applications, such as tracing the light-driven path of electrons in photosynthesis, or establishing a new conceptual basis for chemistry by naturally linking structure and dynamics. It could also help drive innovation by, for example, allowing the development of more powerful and energy efficient optoelectronic components, helping overcome production barriers to unlock the potential of quantum device technologies, or a deeper understanding of the charge transfer mechanisms in batteries.
This positions XFELs as a classic example of a research infrastructure which, even if not geared towards immediate innovation outcomes, can be leveraged to progress a wide range of research, which could have a significant potential economic impact. Furthermore, new developments in compact XFELs, which may ultimately allow them to be shrunk to tabletop size, may open the door to direct commercial application in chip manufacturing. Such development would be particularly relevant for EU competitiveness, given the current European monopoly on high-end chip lithography machines through ASML.
Anticipatory policymakingX-ray free electron lasers demonstrate the challenges involved in closely tracking the shortest processes in nature: it is difficult, but possible. Better control of the attosecond regime is in reach with existing technology but requires upgrading existing facilities (affecting operation) or creating new ones. The high investment required for such projects makes XFELs a poster case for the need for a European strategy on research and technology infrastructures, as recently launched by the European Commission. Cutting-edge infrastructures like this are attractive sites for research: congregating skills and talent, offering unique opportunities, making such centres the first address for EU scientific cooperation, and not only help promote European researcher mobility, but also attract researchers currently based elsewhere.
Given a renewed European focus on competitiveness, it makes sense to design such projects as cross-cutting initiatives, and to seek opportunities to involve the private sector. An ambitious effort to attain high attosecond precision could develop the EU high-tech supply chain (in fields such as electron sources, superconductor technology, or detectors), helping to secure a leading role for Europe in these sectors, as in the case of projects such as the International Thermonuclear Experimental Reactor (ITER). Combining both attractive centres of excellence and scientific fields and more investment in high-tech industry could also be a potential idea for a moonshot project under the next Horizon Europe programme. This could advance research in a plethora of scientific fields, from quantum science over chemistry to biology. In addition, the potential direct commercial viability of this technology, such as in semiconductor manufacturing, could attract innovative funding. This would perpetuate the tradition of European excellence in this field and enable development of a next-generation technology industry in Europe.
Read this ‘At a glance’ note on ‘What if we could track an electron’s every step?‘ in the Think Tank pages of the European Parliament.
En Slovénie, le nom Prevc est devenu synonyme d'excellence. En une décennie, quatre frères et sœur ont accumulé dix médailles olympiques en saut à ski, hissant cette famille issue d'un petit village de Gorenjska au rang de phénomène sportif mondial.
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