Continuous-mode quantum key distribution with digital signal processing

Chen, Ziyang; Wang, Xiangyu; Yu, Song; Li, Zhengyu; Guo, Hong

doi:10.21203/rs.3.rs-2061153/v1

Cited by 9 publications

(9 citation statements)

References 10 publications

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“…Therefore, it is naive to assume that applying the symmetrization procedure to the multimode state and then reversing the effect by applying a rotation to the measurement data maintains the protocol's performance intact. To achieve this, it is necessary to ensure that the operation that performs rotations in the phase space commutes with the coherent pulse detection system and the constellation symbol estimation, whose description in terms of POVMs is not yet known [7]. Additionally, the symmetrization procedure, which corresponds to a network of beam splitters and phase displacements, becomes impractical in realistic scenarios with a large number of transmitted states.…”

Section: Unconditional Securitymentioning

confidence: 99%

The impact of constellation cardinality on discrete unidimensional CVQKD protocols

Dias

Assis

2021

Quantum Inf Process

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Consider the problem of using a finite set of coherent states to distribute secret keys over a quantum channel. It is known that computing the exact secret key rate in this scenario is intractable due to the infinite dimensionality of the Hilbert spaces and usually one computes a lower bound using a Gaussian equivalent bipartite state in the entangled based version of the protocol, which leads to underestimating the actual protocol capability of generating secret keys for the sake of security. Here, we define the QKD protocol's non-Gaussianity, a function quantifying the amount of secret key rate lost due to assuming a Gaussian model when a non-Gaussian modulation was used, and develop relevant properties for it. We show that if the set of coherent states is induced by a random variable approaching the AWGN channel capacity, then the protocol's non-Gaussianity vanishes, meaning that there is no loss of secret key rate due to the use of a Gaussian model for computing bound on the secret key rate. The numerical results show that by using a 256-QAM with Gauss-Hermite shaping, the loss of secret key rate quickly falls below 10 −5 as the distance increases.

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Section: Unconditional Securitymentioning

confidence: 99%

The impact of constellation cardinality on discrete unidimensional CVQKD protocols

Dias

Assis

2021

Quantum Inf Process

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“…SOP's jitter directly causes the quantum signal's attenuation at single polarization, which is equivalent to channel attenuation in a single polarization system, so it can be considered a linear process. Digital signal processing (DSP) method plays a vital importance on current LLO systems, in addition to traditional data post-processing [32]- [34], DSP algorithms for recovering quantum signals have received extensive attention [31], [35], [36] and new analysis methodology is proposed recently [37]. Thus, in addition to KF, we also list other digital data processing method to achieve final secret key rate.…”

Section: Introductionmentioning

confidence: 99%

Experimental Demonstration of LLO Continuous-Variable Quantum Key Distribution With Polarization Loss Compensation

et al. 2023

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The compensation process for the state of polarization (SOP) from quantum signal plays an important role in the practical implementation of continuous-variable quantum key distribution (CV-QKD). In contrast to the previous scheme using an expensive digital dynamic polarization controller, we choose a cheaper manual polarization controller interfaced with a digital algorithm based on Kalman filter to achieve compensation of the polarization loss under the condition that the SOP of the fiber is relatively stable. This paper also enumerates the details of other digital signal processing method to achieve final secret key rate. And a pilot-sequential Gaussian modulated coherent state (GMCS) continuous-variable quantum key distribution system with a local local oscillator (LLO) is experimentally implemented based on the analysis of excess noise. Finally, the experimental results show that the method of polarization loss compensation takes advantages in maintaining the stability of the final secret key rate. And a secret key rate of 110 kbps is achieved within 20 km optical fiber (with 4 dB loss) under the finite-size block of 1 × 10 6 during a more extended time in the laboratory.

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“…In addition, CV-QKD is much easier to be integrated on chips [8]. Due to its powerful advantages, significant progress of CV-QKD has been developed in the field of theoretical analysis [9][10][11][12][13][14][15][16][17] as well as experimental implementation [4,[18][19][20][21][22][23][24][25] up to now.…”

Section: Introductionmentioning

confidence: 99%

Countermeasure for Negative Impact of a Practical Source in Continuous-Variable Measurement-Device-Independent Quantum Key Distribution

et al. 2023

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Continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) can defend all attacks on the measurement devices fundamentally. Consequently, higher requirements are put forward for the source of CV-MDI QKD system. However, the imperfections of actual source brings practical security risks to the CV-MDI QKD system. Therefore, the characteristics of the realistic source must be controlled in real time to guarantee the practical security of the CV-MDI QKD system. Here we propose a countermeasure for negative impact introduced by the actual source in the CV-MDI QKD system based on one-time-calibration method, not only eliminating the loophole induced from the relative intensity noise (RIN) which is part of the source noise, but also modeling the source noise thus improving the performance. In particular, three cases in terms of whether the preparation noise of the practical sources are defined or not, where only one of the users or both two users operate monitoring on their respective source outputs, are investigated. The simulation results show that the estimated secret key rate without our proposed scheme is about 10.7 times higher than the realistic rate at 18 km transmission distance when the variance of RIN is only 0.4. What's worse, the difference becomes greater and greater with the increase of the variance of RIN. Thus, our proposed scheme makes sense in further completing the practical security of CV-MDI QKD system. In other words, our work enables CV-MDI QKD system not only to resist all attacks against detectors, but also to close the vulnerability caused by the actual source, thus making the scheme closer to practical security.

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Continuous-mode quantum key distribution with digital signal processing

Cited by 9 publications

References 10 publications

The impact of constellation cardinality on discrete unidimensional CVQKD protocols

The impact of constellation cardinality on discrete unidimensional CVQKD protocols

Experimental Demonstration of LLO Continuous-Variable Quantum Key Distribution With Polarization Loss Compensation

Countermeasure for Negative Impact of a Practical Source in Continuous-Variable Measurement-Device-Independent Quantum Key Distribution

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