A collaborative research effort involving Sungkyunkwan University (SKKU), the University of Wisconsin–Madison, and the University of Washington has identified a novel atomic defect in zinc oxide (ZnO) that shows significant potential as a high-performance spin qubit. The findings, published in PRX Quantum, detail a molybdenum–oxygen-vacancy complex that could serve as a foundational component for future quantum computing, sensing, and communication technologies.
While nitrogen-vacancy (NV) centers in diamond have traditionally been the leading candidate for solid-state spin qubits due to their ability to maintain quantum information at higher temperatures, the material faces significant industrial hurdles. Diamond is difficult to grow in large-area, high-quality crystals and is largely incompatible with standard semiconductor fabrication processes, complicating the path toward mass production and device integration.
To circumvent these limitations, the research team utilized advanced first-principles quantum simulations on supercomputers to screen potential defects within zinc oxide. Chosen for its "magnetically quiet" nature and its established role in the semiconductor industry, zinc oxide provided an ideal host for quantum information. The team successfully designed a defect structure where a molybdenum atom replaces a zinc atom adjacent to an oxygen vacancy.
The theoretical analysis revealed that this specific defect exhibits exceptional properties, including bright, efficient emission in the visible light spectrum and a low Huang-Rhys factor, which minimizes energy loss through crystal vibrations. Furthermore, the defect's electron spin demonstrated a projected coherence time of approximately 4 milliseconds, even amidst magnetic noise. These characteristics, alongside the potential for high-fidelity "single-shot readout," are critical for the advancement of quantum error correction and large-scale quantum networks.
The significance of this discovery lies in its compatibility with existing manufacturing ecosystems. Because zinc oxide is a well-understood semiconductor, the molybdenum-based defect could offer a scalable platform for integrated quantum devices. Professor Hosung Seo noted that the feasibility of such a robust spin qubit in a representative oxide semiconductor could bridge the gap between theoretical quantum research and the development of integrated, scalable quantum hardware.