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Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Efficient quantum key distribution based on pulse-position modulation

Yequn Zhang, Ivan B. Djordjević, Mark Allen Neifeld

Published Oct 13, 2014• 1 citation
Publisher

Abstract

Pulse-position modulation (PPM) is a promising technique that can be used to improve the efficiency of quantum key distribution (QKD) based on a Poisson photon source. In this paper, we first investigate a simple entanglement-and- PPM-based QKD protocol and demonstrate the improvement in secret key rate. However, such a PPM-based QKD protocol that utilizes only frames with a single click is still inefficient because it ignores frames with two and more clicks. For this reason we propose to use such multi-click frames to further improve the efficiency of PPM-based QKD by employing a better sifting strategy. Specifically, we focus on using the frames with two clicks in addition to those with a single click. Finally, we analyze the secret key rate under various noise levels in the scenario of high channel loss, which has been faced by most QKD applications. With the analytical results, we show the advantage of the proposed PPM-based QKD.

DOI
10.1117/12.2067135

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Pulse-position modulation (PPM) is a promising technique that can be used to improve the efficiency of quantum key distribution (QKD) based on a Poisson photon source. In this paper, we first investigate a simple entanglement-and- PPM-based QKD protocol and demonstrate the improvement in secret key rate. However, such a PPM-based QKD protocol that utilizes only frames with a single click is still inefficient because it ignores frames with two and more clicks. For this reason we propose to use such multi-click frames to further improve the efficiency of PPM-based QKD by employing a better sifting strategy. Specifically, we focus on using the frames with two clicks in addition to those with a single click. Finally, we analyze the secret key rate under various noise levels in the scenario of high channel loss, which has been faced by most QKD applications. With the analytical results, we show the advantage of the proposed PPM-based QKD.
In this paper, we consider quantum key distribution (QKD) using pulse-position modulation (PPM) and propose the PPM-based BB84 QKD protocol. With the adoption of PPM, the efficiency of utilizing weak laser pulses can be improved and hence the key rate. We first analyse the potential of using PPM from the perspective of raw key rate. We then provide detailed description of the proposed protocol, the encoding rule of which has to be specifically designed in order to be secure. Lastly, we consider the intercept-resend and photon-number splitting attacks and analyse the secret key rate of the proposed QKD protocol. Our analysis shows that in high-loss channel, the proposed PPM-based BB84 protocol can achieve higher secret key rates compared to the conventional BB84 protocol.
High-dimensional quantum key distribution (QKD) systems that exploit temporal correlation among entangled photons are of growing practical interest. In such systems, the observation time is typically partitioned into frames of fixed duration, with pulse-position modulation (PPM) coding used within each frame, via which a secret key is established between the parties. Such schemes can be very inefficient in their use of photons, since only a fraction of the frames can be used. As an alternative, we describe an efficient class of schemes with adaptive frame size whose performance can converge to the fundamental limit much more quickly. We analyze and compare the performances of both fixed and adaptive PPM schemes, taking into account photon transmission and detection losses. Further numerical results reveal the significant performance gain of adaptive PPM relative to fixed PPM.
The binary (one-bit-per-photon) encoding that most existing quantum key distribution (QKD) protocols employ puts a fundamental limit on their achievable key rates, especially under high channel loss conditions associated with long-distance fiber-optic or satellite-to-ground links. Inspired by the pulse-position-modulation (PPM) approach to photon-starved classical communications, we design and demonstrate the first PPM-QKD, whose security against collective attacks is established through continuous-variable entanglement measurements that also enable a novel decoy-state protocol performed conveniently in post processing. We achieve a throughput of 8.0 Mbit/s (2.5 Mbit/s for loss equivalent to 25 km of fiber) and secret-key capacity up to 4.0 bits per detected photon, thus demonstrating the significant enhancement afforded by high-dimensional encoding. These results point to a new avenue for realizing high-throughput satellite-based or long-haul fiber-optic quantum communications beyond their photon-reception-rate limits.
In this paper, we propose a quantum key distribution (QKD) protocol based on the protocol of Bennett in 1992 (Phys Rev Lett, 68 3121, 1992) which utilized the pulse position modulation (PPM) and the orbital angular momentum (OAM) to improve the key rate and increase secure transmission distance. In our protocol, we apply PPM technology to B92 protocol (PPM-B92) to increase the key rate. In general, for an optical pulse with the average photon number μ = 0.1, we know that the empty photons is as high as 90.48%. In our protocol, there is only one time slot with photon pulses, and the photons in the pulses carry the log2 M bit information, so the key rate is improved. Bob only modulates the legal time slots to improve the efficiency of the protocol. Secondly, we apply orbital angular momentum (OAM) to the PPM-B92 protocol (PPM-OAM-B92) to increase secure transmission. OAM has rotation invariance, which solves the dependence of base. Through the MATLAB simulation results, we can see that the key rate of the PPM-B92 protocol is always higher than B92's. The PPM-OAM-B92 protocol can accommodate channel transmission loss up to 29dB.
We investigate modulation and coding techniques that approach the fundamental limits of communication and key distribution over optical channels, in the regime of simultaneously high photon and bandwidth efficiencies. First, we develop a simple and robust system design for free-space optical communication that incorporates pulse-position modulation (PPM) over multiple spatial degrees of freedom in order to achieve high photon and spectral efficiency. Further, in the context of key distribution, we determine the optimal rate using a Poisson source of entangled photon pairs and photon detectors, and show how to approach it using PPM parsing of the detected photon stream.
Abstract Up to now, there are only a few studies on the application of pulse position modulation (PPM) and orbital angular momentum (OAM) in measurement-device-independent (MDI) quantum private queries (QPQ) protocols. Given this, we design a QPQ protocol based on PPM-OAM and MDI-QKD (quantum key distribution), i.e. PPM-OAM-MDI-QPQ protocol, which avoids the dependence of the basis besides inheriting the advantages of MDI-QPQ. Our PPM-OAM-MDI-QPQ protocol can achieve longer-distance QPQ and speed up private queries. Moreover, our PPM-OAM-MDI-QPQ protocol can eliminate the basis-dependent flaw and demonstrate a useful technique for high-rate satellite-based QPQ. Meanwhile, our protocol applies quantum memory to achieve the function of a quantum repeater, achieving much longer-distance QPQ.