Boosting the secret key rate in a shared quantum and classical fibre communication system

Abstract

During the last 20 years, the advance of communication technologies has generated multiple exciting applications. However, classical cryptography, commonly adopted to secure current communication systems, can be jeopardized by the advent of quantum computers. Quantum key distribution (QKD) is a promising technology aiming to solve such a security problem. Unfortunately, current implementations of QKD systems show relatively low key rates, demand low channel noise and use ad hoc devices. In this work, we picture how to overcome the rate limitation by using a 37-core fibre to generate 2.86 Mbit s −1 per core that can be space multiplexed into the highest secret key rate of 105.7 Mbit s −1 to date. We also demonstrate, with off-the-shelf equipment, the robustness of the system by co-propagating a classical signal at 370 Gbit s −1 , paving the way for a shared quantum and classical communication network. * dabac@fotonik.dtu.dk, bdali@fotonik.dtu.dk These authors contributed equally to this work 1 arXiv:1911.05360v1 [quant-ph] 13 Nov 2019 of integration with the bright signals used in classical communications [17][18][19][20][21][22][23]. In this work, we show how to overcome the low rate and compatibility limitations by exploiting a 37-core multicore fibre (MCF) as a technology for quantum communications [24]. This technology allows for efficient key generation, enabling the highest secret key rate presented to date. Moreover, we co-propagate in all the 37 cores simultaneously a high-speed classical signal, showing that the quantum communication is only weakly perturbed by it, paving the way for a full-fleshed implementation in current communication infrastructures.

Advances in Silicon Quantum Photonics

“…Quantum communications use a variety of qubit encodings, with timebin, polarisation and spatial modes utilised, depending on application. During the last five years, there have been many achievements in this area, including entangled distribution over 1200 km [277], long distance quantum key distribution [278], underwater quantum communication [279], [280] and largescale quantum and classical multiplexing [281], [282]. All of these demonstrations used bulk-optical components, which limit applicability-integrated photonics instead offer a route to cost-effective QKD, deployed at scale.…”

Surface-Codes-Based Quantum Communication Networks

“…By equipping every node in the proposed QCN by multiple qubit patches, in principle, we can simultaneously perform quantum networking and quantum distributed computing. Instead of wavelength-division multiplexing (WDM), the multicore fiber can also be used to connect the logical qubits [ 16 ]. The proposed QCN does not require the trusted node assumption, but it is assumed that Eve does not have access to SDN controller.…”

“…Quantum information processing (QIP) opens up new avenues for reliable communications, high-precision sensing, and high-performance computing [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Entanglement represents a unique resource for QIP, which allows quantum computers to solve classically intractable problems [ 7 ], provides certifiable security [ 2 ] for data transmissions, and enables sensors to achieve measurement sensitivities beyond the classical limit [ 8 ].…”

Long-distance transmission of quantum key distribution coexisting with classical optical communication over a weakly-coupled few-mode fiber

“…As a primary direction for the future evolution of optical networks, SDM was originally proposed to solve the "capacity crunch" of the single-mode fiber (SMF) [11]. Currently, SDM based on multi-core fiber for the integration between QKD and classical optical communication has been studied [10,12,13].…”