Scalable integration of long-lived quantum memories into a photonic   circuit
  We demonstrate a photonic circuit with integrated long-lived quantum memories. Pre-selected quantum nodes - diamond micro-waveguides containing single, stable, and negatively charged nitrogen vacancy centers - are deterministically integrated into low-loss silicon nitride waveguides. Each quantum memory node efficiently couples into the single-mode waveguide (> 1 Mcps collected into the waveguide) and exhibits long spin coherence times of up to 120 {\mu}s. Our system facilitates the assembly of multiple quantum memories into a photonic integrated circuit with near unity yield, paving the way towards scalable quantum information processing. 
Sara L. Mouradian, Tim Schr\"oder, Carl B. Poitras, Luozhou Li, Jordan   Goldstein, Edward H. Chen, Jaime Cardenas, Matthew ...
physics.optics