Quantum networks: where should we be heading?

Abstract

Quantum key distribution network has become a reality in practical environment. Quantum repeaters have been explored in various physical systems and their combinations. For practical use of them, these new paradigms must be combined with existing or emerging infrastructures of communication and security systems. In this article, we discussed how quantum network can be combined with modern cryptographic technologies in fibre network and with emerging mobile terminals in wireless network, creating new solutions for the future cryptographic and communication systems. Our discussions are summarised in a roadmap.

The Engineering of a Scalable Multi-Site Communications System Utilizing Quantum Key Distribution (QKD)

“…Our research shows how the integration of QKD has implications on the entire systems design, and we suggest new avenues for study in the areas of security and network engineering to make QKD practical for widespread use. We concur with the ultimate goal cited in [2]: to realize a quantumsafe infrastructure in which post-quantum cryptography, QKD, and physical-layer cryptography will be integrated.…”

“…3 As in class 4, but no key refresh occurs. 2 As in class 3, but if insufficient new quantum key material is currently available, then key extension will occur to generate a session key from the current material. A suitable key expansion technique may also be utilized, such as the Rijndael key schedule in AES [17].…”

Coherent Conversion Between Microwave and Optical Photons—An Overview of Physical Implementations

“…Proposals for novel quantum information processing techniques often rely on a quantum network, linking together multiple qubits or groups of qubits to enable quantum‐secure communication, novel metrology techniques, or distributed quantum computing . However, microwave frequency photons are difficult to transmit over long distances—typical attenuation in low‐loss microwave cables at 10 GHz is more than 1 dB m −1 , which compares very poorly with optical fibres with losses below 0.2 dB km −1 at telecom wavelengths (, ).…”

Field-Trial of Machine Learning-Assisted Quantum Key Distribution (QKD) Networking with SDN

“…Integrating quantum key distribution (QKD) with existing "conventional" DWDM fibre networks is crucial for bringing the implementation and commercialisation of quantum networks into reality 1 . In addressing the coexistence of quantumencoded photons with high-intensity classical signals in C-band, the main challenge is the photoninduced noise falling in the quantum channel (Ch-QKD) that deteriorates the Ch-QKD quality and the generated secret key rate (SKR).…”