NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Nat Commun. 2013;4:2725. doi: 10.1038/ncomms3725.
Integrated quantum optical circuits are now seen as one of the most promising approaches with which to realize single-photon quantum information processing. Many of the core elements for such circuits have been realized, including sources, gates and detectors. However, a significant missing function necessary for photonic quantum information processing on-chip is a buffer, where single photons are stored for a short period of time to facilitate circuit synchronization. Here we report an on-chip single-photon buffer based on coupled resonator optical waveguides (CROW) consisting of 400 high-Q photonic crystal line-defect nanocavities. By using the CROW, a pulsed single photon is successfully buffered for 150 ps with 50-ps tunability while maintaining its non-classical properties. Furthermore, we show that our buffer preserves entanglement by storing and retrieving one photon from a time-bin entangled state. This is a significant step towards an all-optical integrated quantum information processor.
集成量子光学电路被视为实现单光子量子信息处理最有前途的方法之一。许多这样的电路的核心元件已经实现，包括光源、门和探测器。然而，对于在芯片上进行光子量子信息处理来说，一个重要的缺失功能是缓冲器，它可以将单光子短时间存储起来，以方便电路同步。在这里，我们报告了一种基于耦合谐振器光波导（CROW）的片上单光子缓冲器，它由 400 个高 Q 值光子晶体线缺陷纳米腔组成。通过使用 CROW，我们成功地将一个脉冲单光子缓冲了 150 ps，可调谐时间为 50 ps，同时保持其非经典特性。此外，我们还表明，我们的缓冲器通过存储和从时间-bin 纠缠态中检索一个光子来保持纠缠。这是朝着全光集成量子信息处理器迈出的重要一步。
