EAGER: Enabling Quantum Leap: Scalable, Controllable and Tunable Room-Temperature Quantum Emitters in Monolayer WSe2

Columbia University, New York NY

Investigators

Abstract

Nontechnical description: Many modern technologies - including low-energy-consumption light bulbs, traffic lights, lasers, and computers - rely on the controlled emission of light. Light is composed of individual packets of energy called photons, and this project seeks to demonstrate the ultimate control of light emission by creating a device architecture capable of emitting single optical photons at will while also tuning their color in real time. While some new classes of tunable light emitters have recently been discovered, most of them operate only at very cold temperatures (less than -420 degrees Fahrenheit). The project is developing an approach for overcoming this major limitation by combining new light emitters with miniature antennas, potentially allowing for operation at room temperature - a critical requirement for most optical technologies. The researchers envision applications spanning maximally secure optical communications to the development of quantum computers. This research activity is integrated with efforts to train the next generation of materials scientists, engineers and physicists. These efforts include highly interdisciplinary PhD research, as well as a ''tiered mentoring'' focused summer program titled Engineering the Next Generation, which serves highly motivated underrepresented high school students from local partner schools and involves both lab work and supplemental programming to develop students' academic and professional skills. Technical description: The discovery of single-photon emitters (SPEs) in monolayer WSe2 in 2015 ushered in a revolutionary class of solid-state quantum emitters with potential for deterministic positioning, facile tuning and control capabilities, and integrability into photonic architectures that do not exist for other classes of solid-state quantum emitters. However, a major limitation of these localized light sources is that the bound exciton states on which they rely are only active at cryogenic temperatures below 20 K. Very recently, it has been demonstrated that a model nanoscale architecture, a nano-optical antenna and extrinsic strain due to a nanobubble, activates the optical activity of bound exciton states at room temperature and under ambient conditions in monolayer WSe2. The overall objective of this project is to establish that the newly discovered room-temperature localized bound exciton states can be developed into tunable SPEs for quantum photonic technologies. The research is organized into two tasks: (1) directly probing the new class of room-temperature emitters to understand their origin and activation, and to identify potential pathways to develop optimized SPEs; and (2) leveraging the new knowledge of these emitters to implement a nanoplasmonic-WSe2 architecture demonstrating activated, tunable room-temperature SPEs. The envisioned emitter architecture consists of a monolayer of WSe2 overlaid on top of a nanoneedle plasmonic antenna, which is able to simultaneously provide the localized strain and nano-optical activation of the bound excitons. The detailed study of these room-temperature localized bound exciton states fills key knowledge voids currently limiting the development of quantum technologies in high-quality 2-dimensional semiconductors. More broadly, a demonstration of large-scale, tunable on-chip room-temperature SPE pixel arrays immediately impacts next-generation device design, providing a direct pathway to SPE technologies for quantum logic applications. These research objectives are integrated with educational efforts that emphasize mentoring and hands-on learning about photonic materials for students in high school through the graduate level. 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.