Improving the performance of the four-state continuous-variable quantum key distribution by using optical amplifiers

Zhang, Heng; Fang, Jianzhang; He, Guangqiang

doi:10.1103/physreva.86.022338

Cited by 62 publications

(39 citation statements)

References 17 publications

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“…Although the EB version does not correspond to the actual implementation, it is fully equivalent to the PM version from the a secure point of view [22,23], and it provides a powerful description of establishing security proof against collective attacks through the covariance matrix γ AB of the state before their respective measurements [25,26].…”

Section: A the Pm And Eb Description Of Four-state Cvqkd Protocolmentioning

confidence: 99%

“…refers here to the mutual information between Alice and Bob [26], S BE is the Holevo bound for the mutual information shared by Eve and Bob, and β < 1 is the reconciliation efficiency (β > 0.8 can be reached for arbitrary low SNR in the four-state CVQKD protocol [22,23]). As shown in [22], S BE is maximized when the state ρ AB shared by Alice and Bob is a Gaussian state, which means S BE is upper bounded by the same quantity computed for a Gaussian state ρ G AB with the same covariance matrix as the state ρ AB in an EB version of the protocol [23].…”

Section: B Secure Key Rate Of Four-state Cvqkd Protocolmentioning

confidence: 99%

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Improving the maximum transmission distance of four-state continuous-variable quantum key distribution by using a noiseless linear amplifier

Tang

Chen

et al. 2013

Phys. Rev. A

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Section: A the Pm And Eb Description Of Four-state Cvqkd Protocolmentioning

confidence: 99%

Section: B Secure Key Rate Of Four-state Cvqkd Protocolmentioning

confidence: 99%

Improving the maximum transmission distance of four-state continuous-variable quantum key distribution by using a noiseless linear amplifier

Tang

Chen

et al. 2013

Phys. Rev. A

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“…For decades, continuous-variable (CV) QKD [6][7][8][9][10][11][12][13] has been a hotspot of QKD research due to its simple implementation with state-of-art techniques [14,15]. It has been shown to be secure against arbitrary collective attacks, which are optimal in both the asymptotic limit [12,13,16,17] and the finite-size regime [18,19].…”

Section: Introductionmentioning

confidence: 99%

Long-distance continuous-variable quantum key distribution using non-Gaussian state-discrimination detection

et al. 2018

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We propose a long-distance continuous-variable quantum key distribution (CVQKD) with a four-state protocol using non-Gaussian state-discrimination detection. A photon subtraction operation, which is deployed at the transmitter, is used for splitting the signal required for generating the non-Gaussian operation to lengthen the maximum transmission distance of the CVQKD. Whereby an improved statediscrimination detector, which can be deemed as an optimized quantum measurement that allows the discrimination of nonorthogonal coherent states beating the standard quantum limit, is applied at the receiver to codetermine the measurement result with the conventional coherent detector. By tactfully exploiting the multiplexing technique, the resulting signals can be simultaneously transmitted through an untrusted quantum channel, and subsequently sent to the state-discrimination detector and coherent detector, respectively. Security analysis shows that the proposed scheme can lengthen the maximum transmission distance up to hundreds of kilometers. Furthermore, by taking the finite-size effect and composable security into account we obtain the tightest bound of the secure distance, which is more practical than that obtained in the asymptotic limit.is relatively hard to design and implement. Fortunately, there exists another way to solve the problem, that is, using discrete modulation such as the four-state CVQKD protocol, proposed by Leverrier et al [13]. This discretely modulated CVQKD generates four nonorthogonal coherent states and exploits the sign of the measured quadrature of each state to encode information rather than using the quadraturex orp itself. This is the reason that the sign of the measured quadrature is already the discrete value to which the most excellent error-correcting codes are suitable even at very low SNR. Consequently, the four-state CVQKD protocol has the merits of both high reconciliation efficiency in the long-distance transmission and the security proof of CVQKD so that it could improve the maximal transmission distance of CVQKD.Currently, photon-subtraction operation, which is a kind of non-Gaussian operation in essence, has been demonstrated theoretically and experimentally to extend the transmission distance of the CVQKD using two-mode entangled states [23][24][25] due to the fact that a suitable photon-subtraction operation would increase the entanglement degree of two-mode entangled state and thereby increase the correlation between the two output modes of two-mode entangled state. Since the entanglement-based (EB) scheme is equivalent to the prepare-and-measure (PM) one, this operation can be employed practically implemented in protocols using coherent states with existing technologies.Furthermore, although a high-speed and high-efficiency homodyne or heterodyne detector can be used effectively to measure the received quantum state, the inherent quantum uncertainty (noise) still prevents the nonorthogonal coherent states from being distinguished with perfect accuracy [26][27][28]. Even if ...

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“…The SKRs for the QPSK-based protocol with coherent detection can be determined with the assumption of collective eavesdropping attacks, as discussed in [12]. At Bob's side, the electric field of LO laser is denoted as The photocurrents of the in-phase and quadrature arms after coherent receiver can be expressed as:…”

Section: Rf-assisted Four-state Cv-qkd System Modelmentioning

confidence: 99%

“…CV-QKD protocols based on coherent states with Gaussian modulation have been proved to be unconditionally secure against collective attacks [11]. In addition, CV-QKD protocols based on discrete modulation, e.g., the four-state protocol has been demonstrated to be secure against collective attacks and introduced for the facility of high reconciliation efficiency [12,13]. Currently, the best candidate for reconciliation is a low-density parity-check (LDPC) coding, which has been realized in real-time with the help of FPGAs [14,15].…”

Section: Introductionmentioning

confidence: 99%

High-speed continuous-variable quantum key distribution over atmospheric turbulent channels

Djordjević

2017

SPIE Proceedings

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We experimentally demonstrate a RF-assisted four-state continuous-variable quantum key distribution (CV-QKD) system in the presence of turbulence. The atmospheric turbulence channel is emulated by two spatial light modulators (SLMs) on which two randomly generated azimuthal phase patterns are recorded yielding Andrews' azimuthal phase spectrum. Frequency and phase locking are not required in our system thanks to the proposed digital phase noise cancellation (PNC) stage. Besides, the transmittance fluctuation can be monitored accurately by the DC level in this PNC stage, which is free of post-processing noise. The mean excess noise is measured to be 0.014, and the maximum secret key rate of >20Mbit/s can be obtained with the transmittance of 0.85, while employing the commercial PIN photodetectors.

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Improving the performance of the four-state continuous-variable quantum key distribution by using optical amplifiers

Cited by 62 publications

References 17 publications

Improving the maximum transmission distance of four-state continuous-variable quantum key distribution by using a noiseless linear amplifier

Improving the maximum transmission distance of four-state continuous-variable quantum key distribution by using a noiseless linear amplifier

Long-distance continuous-variable quantum key distribution using non-Gaussian state-discrimination detection

High-speed continuous-variable quantum key distribution over atmospheric turbulent channels

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