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CRC Press eBooks

Integrated nanophotonics for multi-user quantum key distribution networks

Han Chuen Lim, Mao Tong Liu

Published Aug 21, 2017• 0 citations
Publisher

Abstract

This chapter discusses the developments in the field of integrated nanophotonics for multi-user quantum key distribution (QKD) networks. It begins with the significance of QKD and presents some of the challenges faced by researchers and system developers, especially regarding the key rate, transmission distance, and implementation cost. The chapter considers various options to implement a multi- user QKD network compatible with the existing fiber-optic network infrastructure. It describes entanglement-based QKD and its wavelength-multiplexed implementation enabling efficient use of the available optical fiber bandwidth for QKD. The chapter shows how a centralized broadband entangled-photon source can be shared by many users in an access network and explains the benefits of wavelength- multiplexed entanglement distribution. It looks at recent advances in integrated broadband entangled-photon sources, waveguide-integrated photon detectors, and low-loss integrated passive devices. The chapter also provides an outlook for future research and development in this direction.

DOI
10.1201/9781315153063-14

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This chapter discusses the developments in the field of integrated nanophotonics for multi-user quantum key distribution (QKD) networks. It begins with the significance of QKD and presents some of the challenges faced by researchers and system developers, especially regarding the key rate, transmission distance, and implementation cost. The chapter considers various options to implement a multi- user QKD network compatible with the existing fiber-optic network infrastructure. It describes entanglement-based QKD and its wavelength-multiplexed implementation enabling efficient use of the available optical fiber bandwidth for QKD. The chapter shows how a centralized broadband entangled-photon source can be shared by many users in an access network and explains the benefits of wavelength- multiplexed entanglement distribution. It looks at recent advances in integrated broadband entangled-photon sources, waveguide-integrated photon detectors, and low-loss integrated passive devices. The chapter also provides an outlook for future research and development in this direction.
It is well known that optical access networks are able to provide high data rates over long distances and to a reasonable number of users. Security and privacy are always a challenge for public accessible network infrastructures. Especially in time-division multiplexing passive optical networks (TDM-PONs), in which the downstream signal is broadcasted to all users connected via the same wavelength channel in a shared fiber link, privacy can be a critical concern. Although encryption at the application layer can provide a high level of security, this can be achieved only if the encryption key distribution is perfectly save. On the other hand, encryption on the physical layer such as quantum cryptography or, more precisely, quantum key distribution (QKD) is a very promising approach to achieve secure communication. However, there remain several issues that have to be solved before the quantum cryptography reaches the maturity level needed for a cost effective implementation in practical networks. In this paper, we address quantum key distribution (QKD) over passive optical access networks, which is an enabling technology required to cost efficiently deploy practical quantum encrypted data communication in the access area. We study different methods to integrate QKD systems in conventional optical access networks and quantitatively evaluate their suitability for a potential implementation.
To achieve commercial scalability, fiber-based quantum key distribution (QKD) systems must be integrated into existing optical communication infrastructures, rather than deployed exclusively on dedicated dark fibers. Integrating QKD into optical access networks (OANs) would be particularly advantageous, as these networks provide direct connectivity to end users for whom security is critical. Such integration can address the inherent security vulnerabilities in current OANs, which are primarily based on time-division multiplexing passive optical networks (TDM-PONs). However, integrating QKD into PONs poses significant challenges due to Raman noise and other detrimental effects induced by PON signals, which intensify as the launched power of PONs increases to support higher transmission speeds. In this study, we review recent advancements in both QKD and access network technologies, evaluate the technical feasibility of QKD-OAN integration, and propose cost-effective strategies to facilitate the widespread deployment of QKD in future access networks.
Quantum key distribution (QKD) is a crucial technology for information security in the future. Developing simple and efficient ways to establish QKD among multiple users is important to extend the applications of QKD in communication networks. Herein, we proposed a scheme of symmetric dispersive optics QKD and demonstrated an entanglement-based quantum network based on it. In the experiment, a broadband entangled photon pair source was shared by end users via wavelength and space division multiplexing. The wide spectrum of generated entangled photon pairs was divided into 16 combinations of frequency-conjugate channels. Photon pairs in each channel combination supported a fully connected subnet with eight users by a passive beam splitter. Eventually, it showed that an entanglement-based QKD network over 100 users could be supported by one entangled photon pair source in this architecture. It has great potential on applications of local quantum networks with large user number.
Quantum key distribution (QKD) is a crucial technology for information security in the future. Developing simple and efficient ways to establish QKD among multiple users are important to extend the applications of QKD in communication networks. Herein, we proposed a scheme of symmetric dispersive optics QKD (DO-QKD) and demonstrated an entanglement-based quantum network based on it. In the experiment, a broadband entanglement photon pair source was shared by end users via wavelength and space division multiplexing. The wide spectrum of generated entangled photon pairs was divided into 16 combinations of frequency-conjugate channels. Photon pairs in each channel combination supported a fully-connected subnet with 8 users by a passive beam splitter. Eventually, it showed that an entanglement-based QKD network over 100 users could be supported by one entangled photon pair source in this architecture. It has great potential on applications of local quantum networks with large user number.
Future communications networks not only should enable massive exchange of classical bits, but also the transmission of quantum bits on which many quantum applications rely. This will be the key to offering quantum technologies in a cost-efficient way, and it should encompass the integration of quantum and classical networks at the core of existing optical communications networks, as well as at the access end of such networks. In this work, we cover a range of proposals that enable such an integration for one of the imminent applications of quantum technologies, i.e., quantum key distribution (QKD), by which users can securely exchange a secret key for their cryptographic needs. This will include using wavelength division multiplexing techniques to send quantum and classical data on the same fiber as well as wireless access for QKD users to passive optical networks. In each case, we explore optimal arrangements to find the best way forward for an amicable coexistence.
Entanglement-based quantum key distribution (e-QKD) is a cornerstone of quantum-secure communication, offering advantages in device-independent security, compatibility with quantum networks, and resilience to specific attacks. While the probabilistic nature of entangled photon generation has slowed down experimental adoption compared to prepare-and-measure approaches, deterministic solid-state emitters—particularly epitaxial quantum dots (QDs)—have recently emerged as promising candidates for scalable, high-rate implementations. In this review, we survey the main e-QKD protocols along with their practical requirements and assess current technologies for entangled photon pair generation. We place particular emphasis on the state of the art in QD-based entangled photon sources, analyzing design strategies and performance metrics that directly impact secure key generation. Recent experimental advances demonstrating entanglement distribution and e-QKD with QDs over both fiber and free-space channels are discussed in detail. We conclude with an outlook on remaining challenges in source engineering, transmission capacity, and system integration, highlighting the potential of QDs to enable next-generation quantum communication technologies.