Bosonic Condensation and Emergent Phenomena in 2D Janus layers and Moiré Lattices

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Non-Technical AbstractRecently discovered Janus materials are a new class of ultra-thin crystals. Here, the name ''Janus'' comes from the ancient Roman God of beginnings and transitions with two faces one looking to the future while the other facing to the past. Like Janus himself, Janus materials have top and bottom faces made of different atoms. This unique atomic arrangement brings promising optical properties towards next-generation quantum technologies, especially, if one manages strong interaction between materials and light. This project aims to discover new quantum properties by encapsulating these materials within a special mirror, a Bragg reflector, designed to trap light and achieve strong light-material interaction. While doing so, an innovative educational plan is proposed to train the undergraduate and high school students in an active research environment to create next-generation science and engineering workforce. In parallel, the educational plan introduces ‘Living in a Materials World’ outreach activity to stimulate and prepare K12 students for careers in sciences and engineering through monthly and quarterly online and in-person lab tours, demonstration, and tutorial events.Technical AbstractRecent studies have demonstrated exciton-polaritons in two-dimensional excitonic dichalcogenides. These bosonic quasi-particles have highly appealing properties and functionalities that are not accessible with excitons alone. Exciting new material properties are possible if the density of exciton-polaritons is sufficiently increased to form polariton Bose condensates. Here, owing to the presence of colossal dipole moment and dipolar excitons, Janus layers offer extended exciton lifetimes, exotic valley-physics, and non-linear properties that are ideal for reaching this quantum regime. As such, this project first aims to stabilize exciton-polaritons in the strong-coupling regime by encapsulating 2D Janus layers in designer high-Q factor microcavities. Systematic studies next aim to demonstrate Bose polariton condensates in the high-density regime and establish their quantum properties. Lastly, the research team investigates the formation of topological excitons, controls the super-radiant phase formation, and explores new regimes of Bose-Hubbard physics by using their Moiré lattices and tuning its potential landscape. Once completed, the introduced Janus and Moiré exciton-polaritons, polariton condensates, and topological excitons are anticipated to fill a large fundamental knowledge gap in the field. Potential societal impacts include high-temperature polaritonic lasers and new quantum information devices as well as educational training activities for high school and undergraduate students.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.