Composable finite-size effects in free-space CV-QKD systems

Hosseinidehaj, Nedasadat; Walk, Nathan; Ralph, Timothy C.

doi:10.48550/arxiv.2002.03476

Cited by 4 publications

(6 citation statements)

References 63 publications

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“…[50,51] in the setting of asymptotic security, and more recently re-considered by Refs. [52,53]. In particular, the latter two works provide independent approaches (complementary to ours) for the finite-size study of free-space QKD.…”

Section: Setups With Trusted Loss and Noisementioning

confidence: 90%

Limits and Security of Free-Space Quantum Communications

Pirandola

2020

Preprint

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The study of free-space quantum communications requires tools from quantum information theory, optics and turbulence theory. Here we combine these tools to bound the ultimate rates for key (and entanglement) distribution through a free-space link, where the propagation of quantum systems is generally affected by diffraction, atmospheric extinction, turbulence, pointing errors, and background noise. Besides establishing ultimate limits, we also show that the composable secret-key rate achievable by a suitable, pilot-guided, coherent-state protocol is sufficiently close to these limits, therefore showing the suitability of free-space channels for high-rate quantum key distribution.

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Section: Setups With Trusted Loss and Noisementioning

confidence: 90%

Limits and Security of Free-Space Quantum Communications

Pirandola

2020

Preprint

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“…They therefore apply to different system models than the diffraction-only loss models we explored here. However, collectively the works of [38,55] and ours illustrate clearly that CV-QKD in the satellite-to-Earth channel is feasible.…”

Section: Cs-hom Cs-hetmentioning

confidence: 57%

“…As we grew close to the completion of our study, two other works related to CV-QKD over satellite-to-Earth channels appeared [38,55]. Different from our study, these latter works had a focus on the large-scale fading effects on the QKD key rates, and different excess noise contributions.…”

Section: Cs-hom Cs-hetmentioning

confidence: 76%

“…We now consider the practical security of the CS-QKD protocols using finite-size analysis. In the security analysis, we consider the Gaussian collective attacks with -security that was first introduced in [34,35] and extended to general attacks in [28,[36][37][38]. In the infinite limit the knowledge of the relevant parameters are exact, but in the finite limit the parameters are estimated with a finite precision.…”

Section: B Finite Key Size Effectsmentioning

confidence: 99%

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Feasibility Assessment For Practical Continuous Variable Quantum Key Distribution Over The Satellite-to-Earth Channel

Kish,

Villaseñor,

Malaney

et al. 2020

Preprint

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Currently, quantum key distribution (QKD) using continuous variable (CV) technology has only been demonstrated over short-range terrestrial links. Here we attempt to answer whether CV-QKD over the much longer satellite-to-Earth channel is feasible. To this end, we first review the concepts and technologies that will enable CV-QKD over the satellite-to-Earth channels. We then consider, in the infinite key limit, the simplest-to-deploy QKD protocols, the coherent state (CS) QKD protocol with homodyne detection and the CS-QKD protocol with heterodyne detection. We then focus on the CS-QKD protocol with heterodyne detection in the pragmatic setting of finite keys, where complete security against general attacks is known. We pay particular attention to the relevant noise terms in the satellite-to-Earth channel and their impact on the secret key rates. In system set-ups where diffraction dominates losses, we find that the main components of the total excess noise are the intensity fluctuations due to scintillation, and the time-of-arrival fluctuations between signal and local oscillator. We conclude that for a wide range of pragmatic system models, CS-QKD with information-theoretic unconditional security in the satellite-to-Earth channel is feasible.

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“…For each elevation, we also do not consider explicitly time-varying transmittance, since changes in channel losses are only due to changes in elevation with time. For discrete variable (DV) protocols, such as BB84, link efficiency fluctuations do not directly impact on the secret key rate, unlike in continuous variable (CV) QKD where this can appear as excess noise leading to a reduction in key [41,42].…”

Section: System Modelmentioning

confidence: 99%

Finite key effects in satellite quantum key distribution

Sidhu¹,

Brougham²,

McArthur³

et al. 2020

Preprint

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Quantum key distribution (QKD) can provide secure means of communication that are robust to general quantum computing attacks. Satellite QKD (SatQKD) presents the means to overcome range limitations in fibre optic-based systems and achieve global coverage but raises a different set of challenges. For low-Earth orbit SatQKD, a major limitation is the restricted time window for quantum signal transmission and highly variable channel loss during a satellite overpass of an optical ground station. Here, we provide a systematic analysis of the finite block size effects on secret key length generation for low latency operation using BB84 weak coherent pulse decoy state protocols. In particular, we look at how the achievable single pass secret key length depends on various system parameters for different overpass geometries and calculate the total long-term-average key length. We find that optimisation of basis bias, pulse probabilities and intensities, and data selection, is crucial for extending the range of satellite trajectories and link efficiencies for which finite-block size keys can be extracted. The results also serve as a guide for system sizing of future SatQKD systems and the performance levels required for sources and detectors.

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Composable finite-size effects in free-space CV-QKD systems

Cited by 4 publications

References 63 publications

Limits and Security of Free-Space Quantum Communications

Limits and Security of Free-Space Quantum Communications

Feasibility Assessment For Practical Continuous Variable Quantum Key Distribution Over The Satellite-to-Earth Channel

Finite key effects in satellite quantum key distribution

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