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arXiv:0911.0745 · Journal of the Optical Society of America B

Optimum design for BB84 quantum key distribution in tree-type passive optical networks

J. Capmany, Carlos R. Fernández‐Pousa

Published May 5, 2010• 8 citations
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Abstract

We show that there is a trade-off between the useful key distribution bit rate and the total length of a deployed fiber in tree-type passive optical networks (PONs) for Bennet and Brassard 1984 protocol (BB84) quantum key distribution applications. A two stage splitting architecture where one splitting is carried in the central office and a second one in the outside plant and a figure of merit to account for the trade-off are proposed. We find that there is an optimum solution for the splitting ratios of both stages in cases of photon number splitting attacks and decoy state transmission. We then analyze the effects of the different relevant physical parameters of the PON on the optimum solution.

DOI
10.1364/josab.27.00a146

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We show that there is a trade-off between the useful key distribution bit rate and the total length of a deployed fiber in tree-type passive optical networks (PONs) for Bennet and Brassard 1984 protocol (BB84) quantum key distribution applications. A two stage splitting architecture where one splitting is carried in the central office and a second one in the outside plant and a figure of merit to account for the trade-off are proposed. We find that there is an optimum solution for the splitting ratios of both stages in cases of photon number splitting attacks and decoy state transmission. We then analyze the effects of the different relevant physical parameters of the PON on the optimum solution.
This paper provides an analysis of the performance of different passive optical network (PON) topologies for the distribution of multiuser quantum keys using subcarrier multiplexing and the Bennet-Brassard (BB84) protocol. PON topologies are evaluated in terms of the achievable quantum bit error rate (QBER) and the useful key rate. Results show that wavelength routed (WR) networks outperform broadcast topologies as the first are not subject to division losses. Within WR architecture the star configuration is the most efficient in terms of network scalability, maximum reachable distance and maximum useful distribution rate. The effect of subcarrier modulation index on the network performance has also been considered showing a similar and non significant impact for the range considered in this paper.
Needs for providing security to end users have brought installation of quantum key distribution (QKD) in one-to-many access networks such as passive optical networks. In the networks, a presence of optical power splitters makes issues for secure key rate more important. However, researches for QKD in access networks have mainly focused on implementation issues rather than protocol development for key rate enhancement. Since secure key rate is theoretically limited by a protocol, researches without protocol development cannot overcome the limit of secure key rate given by a protocol. This brings need of researches for protocol development. In this paper, we provide a new approach which provides secure key rate enhancement over the conventional protocol. Specifically, we propose the secure key rate formula in a passive optical network by extending the secure key rate formula based on the decoy-state BB84 protocol. For a passive optical network, we provide a way that incorporates cooperation across end users. Then, we show that the way can mitigate a photon number splitting (PNS) attack which is crucial in an well known decoy BB84 protocol. Especially, the proposed scheme enables multi-photon states to serve as secure keys unlike the conventional decoy BB84 protocol. Numerical simulations demonstrate that our proposed scheme outperforms the decoy BB84 protocol in secure key rate.
The access network portion of a telecommunications system in the last years demands ever-increasing bandwidth to serve not only residential and commercial customers but also other telecommunications operators, as is the case with back-haul in mobile infrastructure.To achieve this, technologies using fiber optics as a transmission medium are being developed.Passive Optical Network (PON) protocols such as ITU-T G.9804.1 provides new schemes of multiplexing that improve higher speed offered both in the downstream channel (operator to user) and in the upstream channel (user to operator).In some cases a symmetrical optical link is required to support new services, applications and terminals from users side because their profiles and demands has changed in the last decade with new challenges to maintain network parameters within the established contracted values.On the other hand, information security has also been a topic of interest in recent years, so quantum cryptography offers an alternative to increase robustness compared to the mechanisms available in electronic systems that could be vulnerable to the development of quantum computing.Although quantum cryptography protocols were defined in the last century, their application is of interest today, as they can exploit the properties of photons to make it more difficult for an intruder to obtain the private key of an information system that uses optical fiber as a transmission medium.This work shows the computational application of the BB84 quantum key distribution (QKD) protocol on an operating model of a 50G passive optical network, demonstrating both the cryptography performance and network quality parameters such as the bit error rate (BER) and the eye diagram.
Most experimental realizations of quantum key distribution are based on the Bennett-Brassard 1984 (the so-called BB84) protocol. In a typical optical implementation of this scheme, the sender uses an active source to produce the required BB84 signal states. While active state preparation of BB84 signals is a simple and elegant solution in principle, in practice passive state preparation might be desirable in some scenarios, for instance, in those experimental setups operating at high transmission rates. Passive schemes might also be more robust against side-channel attacks than active sources. Typical passive devices involve parametric down-conversion. In this paper, we show that both coherent light and practical single-photon sources are also suitable for passive generation of BB84 signal states. Our method does not require any externally driven element, but only linear optical components and photodetectors. In the case of coherent light, the resulting key rate is similar to the one delivered by an active source. When the sender uses practical single-photon sources, however, the distance covered by a passive transmitter might be longer than that of an active configuration.
Fiber-based quantum key distribution (QKD) systems are mature and commercialized, but their integration into existing optical networks is crucial for their widespread use, in particular in passive optical networks (PONs) if end-to-end quantum-secured communications are to be addressed. While discrete-variable QKD coexistence with classical channels is well-studied in point-to-point links, its performance in point-to-multipoint topologies like PONs has received less attention. We thus developed a numerical tool to estimate quantum-available bandwidth and maximum link lengths for QKD systems in single-fiber PON architectures in coexistence with GPON, XG-PON, NG-PON2, and HS-PON standards. The QKD channel performance is obtained by setting thresholds on the quantum bit error rate and the secret key rate, ultimately limited by spontaneous Raman scattering noise and high optical distribution network losses. We perform a comparison between the performance obtained assuming the asymptotic infinite-key generation rate or taking into account actual implementations in the finite-key regime. We evidence that proper design rules can be obtained as a function of both classical and quantum system parameters to support end-to-end quantum security services in existing optical networks.