We discuss an all-silicon approach that enables miniaturization of Quantum Key Distribution (QKD) components and targets cost effectiveness. This facilitates the widespread adoption of QKD in standard communication infrastructures, opening the door to new application domains currently out of reach with conventional QKD technologies.
Integrated photonics offers great potential for quantum communication devices in terms of complexity, robustness, and scalability. Silicon photonics in particular is a leading platform for quantum photonic technologies, with further benefits of miniaturization, cost-effective device manufacture, and compatibility with CMOS microelectronics. However, effective techniques for high-speed modulation of quantum states in standard silicon photonic platforms have been limited. Here we overcome this limitation and demonstrate high-speed low-error quantum key distribution modulation with silicon photonic devices combining slow thermo-optic DC biases and fast (10 GHz bandwidth) carrier-depletion modulation. The ability to scale up these integrated circuits and incorporate microelectronics opens the way to new and advanced integrated quantum communication technologies and larger adoption of quantumsecured communications.
Quantum key distribution (QKD), a cryptography technology providing information theoretic security based on physical laws, has moved from the research stage to the engineering stage. Although the communication distance is subject to a limitation attributable to the QKD fundamentals, recent research and development of “key relaying” over a “QKD network” is overcoming this limitation. However, there are still barriers to widespread use of QKD integrated with conventional information systems: applicability and development cost. In order to break down these barriers, this paper proposes a new solution for developing secure network infrastructure based on QKD technology to accommodate multiple applications. The proposed solution introduces 3 functions: (1) a directory mechanism to manage multiple applications hosted on the QKD network, (2) a key management method to share and to allocate the keys for multiple applications, and (3) a cryptography communication library enabling existing cryptographic communication software to be ported to the QKD network easily. The proposed solution allows the QKD network to accommodate multiple applications of various types, and moreover, realizes applicability to conventional information systems easily. It also contributes to a reduction in the development cost per information system, since the development cost of the QKD network can be shared between the multiple applications. The proposed solution was implemented with a network emulating QKD technology and evaluated. The evaluation results show that the proposed solution enables the infrastructure of a single QKD network to host multiple applications concurrently, fairly, and effectively through a conventional application programming interface, OpenSSL API. In addition, the overhead of secure session establishment by the proposed solution was quantitatively evaluated and compared.
As a promising quantum application, Quantum Key Distribution (QKD) technology has been rapidly developed from point-to-point communication to a large-scale commercial network. However, considering the cost of QKD components and network infrastructure, building a QKD network is challenged by its expensive capital expenditure, which significantly hinders its future popularization. In this article, we envision an evolution roadmap consisting of three stages for the future development of QKD networks, aiming at achieving a fully integrated network architecture that combines QKD and telecommunications networks. Powered by several critical technologies, such as link multiplexing, miniaturized QKD, and transmission optimization, QKD is foreseen to be integrated into telecommunications networks as an add-on module that can be flexibly deployed. After that, we introduce the integrated network architecture design in detail, and respectively provide four QKD-related function implementations. At last, key technologies that should be concerned and further investigated are also discussed with performance evaluation, which can provide theoretical guidance for both industries and academia. Based on the proposed roadmap and integrated architecture, we believe a scalable, easy-to-use, and affordable QKD service can be brought to current telecommunication networks, and extensively applied by ordinary people while using daily applications.