Cavity Quantum Materials (CAVMAT)

ERC Consolidator Grant awarded by the European Research Council (ERC)

Concept

Light-matter coupling has the potential to modify functional properties of quantum materials to yield the tunability required for quantum-technological applications. However, light-matter control concepts, such as Floquet engineering and light-induced phase transitions, suffer from the requirement of strong laser driving and the lack of coherence on long time scales. Overcoming these key limitations through advancing the infant field of cavity quantum materials is the central objective of CAVMAT.

The main hypothesis behind CAVMAT is that cavity materials engineering combines the effi- ciency of strong-light matter coupling in cavities with the flexibility of Floquet engineering of macroscopic quantum many-body phenomena. CAVMAT aims to explore and expand this new frontier with a combined theoretical-computational effort. The three key objectives of CAVMAT are: (i) To establish cavity-driving schemes that successfully bridge the gap between quantum cavity and semiclassical many-photon Floquet limits. (ii) To propose realistic cavity quantum materials platforms providing guidance for next-generation experiments. (iii) To develop and combine numerical methods that can treat the relevant nonequilibrium electron-polariton prob- lems at short and long time scales. These objectives will be tackled in three work packages, namely WP 1: quantum Floquet engineering, WP 2: plasmonic superconductivity, and WP 3: excited states by design.

The proposed work goes well beyond state-of-the-art in both nonequilibrium quantum many- body systems and quantum optics, and its success will be groundbreaking through providing microscopic underpinnings for pathways towards versatile solid-state platforms for cavity and Floquet physics. The key innovative points of the overall proposal are: (a) Making available so-far largely elusive Floquet engineering in quantum materials well beyond very few existing proof-of-principle demonstrations; (b) Bringing optical tuning of many-body materials phase dia- grams in and out of equilibrium towards (quantum) technological applications, with the potential of significant impact on science and technology in Europe; (c) Deepening and broadening our theoretical understanding of light-matter couplings and its connections to microscopic materials interactions, spontaneous symmetry breaking and topology. CAVMAT is timely and has multi- disciplinary aspects, bridging quantum materials science, nonequilibrium dynamics and ultrafast phenomena, and quantum optics.