CAREER: Engineering Bichromatic Moire Superlattices for Tunable Emerging Quasiparticles and Correlated States

Non-technical Abstract: This project offers an integrated research and education effort centered on programmable quantum materials engineered through the controlled stacking of atomically thin layers. By arranging layers in designed patterns, the project reveals how structure at the nanoscale shapes the material behavior. The research addresses fundamental questions in quantum matter by using a flexible platform to explore tunable quantum states, introducing new ways to program quantum interactions and access dynamic phase transitions that do not occur in natural materials. The educational activities translate these ideas into accessible, hands-on learning experiences through an industry-facing undergraduate experimental course and inclusive K-12 outreach efforts, including interactive demonstrations and classroom-ready kits focused on layered materials and moiré physics. Together, these activities broaden participation, strengthen pathways into STEM for students from diverse backgrounds, and support national priorities in education, workforce development, and innovation. Technical Abstract: The research effort builds on the ability to vertically stack atomically thin two-dimensional layers to engineer heterostructures with lattice mismatch or small relative twist angles. These structures give rise to long-wavelength moiré superlattices that create periodic potentials for controlling electronic and excitonic interactions at the nanoscale. This project introduces a new paradigm that exploits interference between distinct moiré length scales to generate bichromatic supermoiré lattices in van der Waals heterostructures with independently controlled orientations and compositions. The central scientific problem is how engineered interference between multiple periodic length scales enables programmable quantum interactions and collective quantum states. The research goals are to discover and control interacting quasiparticles, including electrons, excitons, and trions, and to establish broadly applicable design principles linking lattice geometry, interaction strength, and emergent quantum behavior. The research team integrates advanced optical spectroscopy and scanning probe microscopy to probe correlated quantum phases, tunable excitonic complexes, and excitonic dynamics, while systematically tuning electric field, carrier density, magnetic field, and optical excitation in situ. By enabling controlled manipulation of hopping processes and Coulomb interactions within a single, reconfigurable platform, the project establishes a new experimental framework for studying dynamic phase transitions and correlated quantum states in engineered two-dimensional materials. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2540941 | Program: 01002930DB NSF RESEARCH & RELATED ACTIVIT,01002627DB NSF RESEARCH & RELATED ACTIVIT,01003031DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Xi Wang | Institution: Washington University, SAINT LOUIS, MO | Award Amount: $548,927 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2540941 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2540941.html