We demonstrate a photonic circuit with integrated long-lived quantum memories. Precharacterized quantum nodes-diamond microwaveguides containing single, stable, negatively charged nitrogenvacancy centers-are deterministically integrated into low-loss silicon nitride waveguides. These quantum nodes efficiently couple into the single-mode waveguides with >1 Mcps collected into the waveguide, have narrow single-scan linewidths below 400 MHz, and exhibit long electron spin coherence times up to 120 μs. Our system facilitates the assembly of multiple quantum nodes with preselected properties into a photonic integrated circuit with near unity yield, paving the way towards the scalable fabrication of quantum information processors.
Mouradian, S. L., Schrï¿½der, T., Poitras, C. B., Li, L., Goldstein, J., Chen, E. H., … Englund, D. (2015). Scalable integration of long-lived quantum memories into a photonic circuit. Physical Review X, 5(3). https://doi.org/10.1103/PhysRevX.5.031009