Flat-Band Quantum Engineering in Twisted 2D Materials with Magneto-optical Exceptional-Surface Cavities

This project develops a transformative platform for stabilizing and controlling strongly correlated quantum phases in twisted two-dimensional (2D) materials through flat-band engineering with magneto-optical exceptional-surface (ES) cavities. Flat-band engineering combined with time-reversal-symmetry (TRS) breaking is essential for achieving stable and accessible exotic phases such as superconductivity, correlated insulators, and topological states. By integrating non-Hermitian photonics, cavity quantum electrodynamics, quantum many-body physics, and 2D material engineering, the project enables non-invasive and tunable control of fragile electronic states. In this approach, TRS breaking is introduced via using magneto-optical material for fabricating cavity, while ES cavities amplify vacuum-fluctuation-material coupling and TRS symmetry breaking for producing a large band-energy shift (ΔE ≥ 10 meV) and extending flat-band stabilization. The experimental program will integrate twisted bilayer graphene and other related 2D materials with high-chirality, small-mode-volume and magneto-optical ES cavities, and probe cavity-induced modifications using angle-resolved photoemission spectroscopy, transport, ultrafast optical and magneto-optical spectroscopy at low temperature. These studies will provide the first direct evidence of ES cavity-enhanced stabilization of correlated phases in 2D materials. The project combines theoretical modeling, numerical simulation, nanofabrication and advanced characterization, hosted by the Photonics group at Aalto University (Prof. Zhipei Sun) with a secondment at the University of Oxford (Prof. Yulin Chen). Together with open-science practices and active gender-diversity mentoring, this fellowship positions ES photonics as a scalable tool for robust and tunable flat-band engineering, establishing a pathway toward next-generation quantum technologies—from superconducting circuits to quantum sensors and correlated-electron devices.