Ultrafast topological engineering of quantum materials

Projektinformationen

UTOPIQ

ID Finanzhilfevereinbarung: 101076639

DOI

10.3030/101076639

EK-Unterschriftsdatum 12 Januar 2023

Startdatum 1 September 2023

Enddatum 31 August 2028

Finanziert unter

• European Research Council (ERC)

Gesamtkosten

€ 1 754 304,00

EU-Beitrag

€ 1 754 304,00

Koordiniert durch

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 1 - UTOPIQ (Ultrafast topological engineering of quantum materials)

Berichtszeitraum: 2023-09-01 bis 2026-02-28

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

The ERC UTOPIQ project explores how light can be used to control the ultrafast behavior of electrons in quantum materials, i.e. materials with exotic electronic properties that could transform electronics and quantum technologies. UTOPIQ is organized into four work packages (WPs). WP1 develops a unique experimental instrument that combines a high-repetition-rate, polarization-tunable extreme ultraviolet (XUV) light source with a momentum microscope. This setup allows capturing the ultrafast dynamics of electrons in photoexcited solids with an unprecedented level of detail. WP2 investigates the emergence and manipulation of Floquet–Bloch states, i.e. exotic electronic states that appear when electrons interact coherently with light pulses. WP3 focuses on light-induced topological phase transitions driven by electronic interactions, while WP4 aims to study ultrafast switching between topological phases via coherent vibrations of the atomic lattice (phonons).

The overall objective of the project is to explore methods for creating new nonequilibrium quantum states with light and to deepen our understanding of light-induced nonequilibrium phenomena in quantum materials.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

In the first two years, UTOPIQ has already achieved major milestones. The high-repetition-rate, polarization-tunable XUV beamline was successfully integrated with the momentum microscope, producing a completely new instrument. Building on this foundation, we demonstrated valley-selective Floquet engineering in 2D materials known as transition metal dichalcogenides (TMDCs). Experiments showed that circularly polarized light can selectively control electrons in different valleys of Floquet–Bloch bands, establishing a new approach to ultrafast valleytronics. These techniques were later extended to additional 2D materials, revealing novel light-matter interaction mechanisms that were not anticipated at the start of the project.

Taken together, the project has delivered several significant accomplishments. The development of the multimodal XUV photoemission microscope represents a major methodological advance, enabling ultrafast XUV photoemission dichroism measurements that were previously impossible. The observation of valley-polarized Floquet–Bloch states directly links Floquet engineering to quantum-geometric light–matter interactions in 2D materials. Moreover, excited-state mapping combined with linear dichroism has uncovered electronic states in topological semimetals that were previously inaccessible, and the enhancement of electron–phonon coupling in nonequilibrium conditions has been demonstrated. Beyond the laboratory, these achievements have already led to rapid dissemination through publications, conferences, and new collaborations with researchers worldwide.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

UTOPIQ’s most notable advance is the experimental realization of valley-selective Floquet–Bloch states, demonstrating a direct connection between light-driven band engineering and polarization-dependent light-matter interactions. While such polarization control of hybrid light–matter states in TMDCs had been predicted theoretically, observing them experimentally was extremely challenging.

Overall, UTOPIQ has combined innovative experimental methods with new physical insights, providing a powerful platform to study and control quantum materials. The results pave the way for ultrafast symmetry-guided manipulation of electronic states, pushing the boundaries of what is currently possible in the field.