Ultrafast topological engineering of quantum materials

Informazioni relative al progetto

UTOPIQ

ID dell’accordo di sovvenzione: 101076639

DOI

10.3030/101076639

Data della firma CE 12 Gennaio 2023

Data di avvio 1 Settembre 2023

Data di completamento 31 Agosto 2028

Finanziato da

• European Research Council (ERC)

Costo totale

€ 1 754 304,00

Contributo UE

€ 1 754 304,00

Coordinato da

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

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

Periodo di rendicontazione: 2023-09-01 al 2026-02-28

Sintesi del contesto e degli obiettivi generali del progetto

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.

Lavoro eseguito dall’inizio del progetto fino alla fine del periodo coperto dalla relazione e principali risultati finora ottenuti

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.

Progressi oltre lo stato dell’arte e potenziale impatto previsto (incluso l’impatto socioeconomico e le implicazioni sociali più ampie del progetto fino ad ora)

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.