Wisconsin Quantum Institute Seminar: Evelyn Hu, Harvard University

Although we usually assume that a "perfect" material is required to produce the best emitters for nano-optical devices, defect states in wide bandgap semiconductors are defining a new frontier for quantum information technologies, offering correlated spin-photon information. Numerous materials platforms have been explored, including single crystal diamond, SiC and Si: ultimately these defect qubits will need to satisfy quantum systems-level requirements for coherence, brightness, and equivalence of states. This talk will introduce some building-block devices for the evaluation of candidate defect qubits, with a focus on Silicon Vacancies in 4H-SiC. Nanobeam photonic crystal cavities serve as both exquisitely sensitive optical amplifiers [1], as well as "nanoscopes" that allow us to better understand the local environment of the silicon vacancies, interactions with proximal defects and pathways to better processing and control of the defects [2]. Forming defects directly into cavities by "Laser Writing" allows more rapid feedback of optimal defect formation conditions [3]. Embedding G-center defects in Si, within PN diodes allows a dynamic assessment of processing conditions and fine-tuning of defect properties [4]. In aggregate, these techniques help to build the foundational understanding to take defect qubits to the “next steps” in implementing new quantum information technologies.

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