Silicon Photonics for Quantum Fibre Networks

如今，安全通信对于敏感信息的交换是必不可少的，而基于经典密码协议的安全性不能绝对保证。特别是当完全容错的量子计算机问世时，经典的加密和解密方法将不再安全，对密码系统构成严重威胁。量子密码学(QCy)是量子通信(QCS)的一个分支，开启了信息传输安全的新纪元。尽管在过去的20年里，量子密钥分发和量子密钥分发(QKD)已经迈出了很大的一步，但量子密钥分发的未来仍然受到主要障碍的挑战。Square项目打破了这些障碍，开发了基于硅光子学的下一代量子设备，实现了紧凑、可靠和高效的组件，从而能够构建完全连接的长距离、高速率QKD安全的量子通信网络。Square项目开发了一种用于量子通信和基于硅光电子的经典通信的全集成发射器(Tx)和接收器(Rx)，这是将集成光子学的资产与CMOS技术相结合的有力手段。硅光子学背后的推动力是，硅代表着一个成熟的集成平台，它将光子电路带入更高的集成水平，允许大规模生产，就像它对电子电路所做的那样。从这个意义上说，我们相信硅光子学将在未来的量子通信中扮演重要的角色，使其能够为量子通信应用建立功能强大且成本效益高的光子电路。Square将开发必要的集成量子技术，以突破当前最先进的限制，并进一步将这些技术直接集成到量子子系统中。因此，这些组件将针对特定量子网络场景中的特定应用进行开发。拟议的新型网络利用不同技术的优势，在覆盖范围、敏感度、复杂性、实用性和总功耗方面获得全球优势。

Nowadays secure communication is essential for exchange of sensitive information, while the security based on classical cryptography protocols cannot be absolutely guaranteed. Especially when a full-tolerant quantum computer will be available, the classical encryption and decryption methods will be no longer secure, posing a serious threat to cryptosystems. Quantum cryptography (QCy), a branch of Quantum Communications (QCs), has opened a new era in the security of information transmission. Although big steps in QCs and Quantum Key Distribution (QKD) have been taken over the last 20 years, the future of QCs is still challenged by major barriers. The SQUARE project shatters these barriers by developing the next generation of quantum devices based on silicon photonics, enabling compact, reliable, and efficient components, allowing for the construction of fully connected long-reach, high-rate QKD-secured quantum communication networks. The SQUARE project develops a fully integrated transmitter (Tx) and receiver (Rx) for quantum communications and classical communication based on silicon photonics, which is a powerful means to combine the assets of integrated photonics with CMOS technologies. The driving force behind silicon photonics is that silicon represents a mature integration platform, which brings photonic circuits to a higher integration level allowing for mass-production as it has done for electronic circuits. In this sense, we believe that silicon photonics will play a significant role in future QCs, allowing to build up powerful and cost-effective photonic circuits for quantum communication applications. SQUARE will develop the integrated quantum technologies necessary to breach the limits of current state-of-the-art, and furthermore integrate these technologies directly in quantum subsystems. Hence the components will be developed for specific applications in specific quantum network scenarios. The proposed novel network leverages on the strengths of different technologies to obtain global benefits in terms of reach, sensitivity, complexity, practicality and total power consumption.