On-chip spin-photon quantum interface based on individually addressable defects in a two- dimensional material

Summary: The objective of this proposal is to develop an on-chip spin-photon interface that incorporates single-photon generation, long-lasting spin coherence, programmable microwave control, and nanophotonic device integration, ideally functioning in ambient conditions. In particular, solid-state electronic spins, serving as quantum bits (qubits), have been employed for quantum sensing of weak signals with high sensitivity; they are capable of detecting electromagnetic fields, temperature¹ , strain^2,3, paramagnetic impurities in liquids and crystals⁴ , and beyond⁵. Moreover, solid-state spins have also shown to exhibit highly coherent optical transitions, allowing the establishment of secure quantum communication channels via spin-photon entanglement across distant quantum systems^6,7. In recent years, two-dimensional (2D) semiconductors hosting optically-active atomic-scale defects have emerged as a promising platform for the development of scalable spin-photon interfaces, leveraging existing semiconductor infrastructure^8–10. However, achieving both robust quantum information processing of solid-state qubits and their on-chip integration with nanophotonic devices has remained elusive so far. To this end, we aim to conduct transformative research by developing error-robust control protocols for individually addressable qubits in a 2D material, as well as integrating them into a nanoscale on-chip device for multifunctional quantum applications. Specifically, we propose utilizing a strong vector magnetic field to engineer the sensor characteristics of a qubit, applying local electric field gating to suppress charge noise, and demonstrating system-tailored optimal control approaches to maximize the fidelity of a hybrid spin-photon interface. This project aims to advance not only the fundamental science of optimally engineering solid-state quantum systems in noisy environments through a combination of theoretical and experimental studies on 2D materials, but also to demonstrate a disruptive leap forward in the practical development of a scalable on-chip quantum device^11,12. The outcome of this research will represent a disruptive advance in the real-world application of a hybrid solid-state quantum platform, extending its utility beyond proof-of-concept demonstrations. For example, a high-sensitivity quantum sensor within 2D materials opens new avenues in interdisciplinary applications, including physics, chemistry, biology, and materials science, requiring precision spectroscopy with high spatial resolution^13-15. The inherent 2D nature of the on-chip quantum processor enables the use of existing infrastructure, ensuring efficiency and accessibility. Moreover, the large-scale 2D integration of solid-state qubits on a nanophotonic device paves the way for a scalable and commercially viable quantum device.