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arxiv: 1907.02207 · v1 · pith:N5UHQEAInew · submitted 2019-07-04 · 🪐 quant-ph

Improving parameter estimation of entropic uncertainty relation in continuous-variable quantum key distribution

Pith reviewed 2026-05-25 09:46 UTC · model grok-4.3

classification 🪐 quant-ph
keywords continuous-variable quantum key distributionentropic uncertainty relationparameter estimationfinite-size effectsdouble-data modulationcomposable securitycovariance matrix
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The pith

Adapting finite-size covariance estimation and reusing every state for both tasks improves entropic uncertainty relation analysis in continuous-variable quantum key distribution.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Security proofs for continuous-variable quantum key distribution that rely on entropic uncertainty relations need reliable estimates of the covariance matrix and the maximum entropy term. Finite-size data produce statistical fluctuations in these estimates, and conventional methods consume extra states solely for parameter estimation. The paper adapts standard estimation techniques to incorporate finite-size corrections on the covariance matrix within the composable security framework. It then introduces double-data modulation so that the same states serve simultaneously for covariance estimation and for key generation, removing the fluctuation that would otherwise appear in the maximum-entropy term.

Core claim

By adapting the parameter-estimation procedure to include finite-size effects on the covariance matrix and by applying double-data modulation that reuses all states for both estimation and key extraction, the leakage rate can be bounded without statistical fluctuation in the max-entropy while preserving the validity of the entropic uncertainty relation under composable security.

What carries the argument

Double-data modulation, a technique that lets every transmitted quantum state contribute to both covariance-matrix estimation and secret-key generation.

If this is right

  • Finite-size fluctuations in the covariance matrix are correctly folded into the EUR leakage estimate.
  • The statistical fluctuation term associated with max-entropy estimation vanishes.
  • The fraction of states sacrificed solely for parameter estimation drops substantially.
  • Practical key rates under the EUR security proof increase for the same total data volume.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The technique may shorten the block length needed to reach positive finite-size key rates.
  • Similar reuse strategies could be tested in other uncertainty-relation proofs that currently discard data for estimation.
  • Implementation would require confirming that the modulation pattern itself does not create detectable side channels.

Load-bearing premise

Reusing the same states for estimation and key generation leaves the entropic uncertainty relation bounds intact and introduces no new side-channel attacks.

What would settle it

An experimental run in which the secret-key rate obtained with double-data modulation falls measurably below the rate predicted by the adapted EUR bound.

Figures

Figures reproduced from arXiv: 1907.02207 by Hong Guo, Song Yu, Xiangyu Wang, Yi-Chen Zhang, Ziyang Chen.

Figure 1
Figure 1. Figure 1: FIG. 1. Prepare-and-measure (PM) scheme of continuous [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Comparison of performances between the previ [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Comparison of performances between the previous [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
read the original abstract

The entropic uncertainty relation (EUR) is of significant importance in the security proof of continuous-variable quantum key distribution under coherent attacks. The parameter estimation in the EUR method contains the estimation of the covariance matrix (CM), as well as the max-entropy. The discussions in previous works have not involved the effect of finite-size on estimating the CM, which will further affect the estimation of leakage information. In this work, we address this issue by adapting the parameter estimation technique to the EUR analysis method under composable security frameworks. We also use the double-data modulation method to improve the parameter estimation step, where all the states can be exploited for both parameter estimation and key generation; thus, the statistical fluctuation of estimating the max-entropy disappears. The result shows that the adapted method can effectively estimate parameters in EUR analysis. Moreover, the double-data modulation method can, to a large extent, save the key consumption, which further improves the performance in practical implementations of the EUR.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript adapts finite-size parameter estimation techniques for covariance matrix analysis to the entropic uncertainty relation (EUR) security proof for continuous-variable QKD under composable security. It further proposes a double-data modulation scheme in which all transmitted states are reused for both parameter estimation and key generation, with the stated effect that statistical fluctuations in the max-entropy term vanish and overall key consumption is reduced while preserving the EUR bounds.

Significance. If the double-data modulation construction is shown to preserve the EUR bounds and composable security without additional finite-size corrections or side-channel assumptions, the work would provide a concrete route to lower the estimation overhead that currently limits practical EUR-based CV-QKD implementations.

major comments (2)
  1. [Section describing double-data modulation (likely §4 or §5)] The central claim that reuse of the same data set for covariance-matrix estimation and max-entropy evaluation eliminates statistical fluctuations (Abstract) requires an explicit joint bound; the manuscript must derive how the estimator for the covariance matrix and the max-entropy term remain independent of the target secret-key rate when the identical quadrature data are shared, or show the additional finite-size correction term that appears.
  2. [Section on adapted parameter estimation under composable security] The adaptation of the parameter-estimation procedure to the composable EUR framework must be shown to avoid circularity: the covariance-matrix elements that enter the EUR bound are themselves estimated from the same data that determine the leakage term; an equation or lemma establishing that the resulting bound remains valid under this dependence is needed.
minor comments (2)
  1. Notation for the estimated covariance matrix elements should be introduced once and used consistently; several symbols appear to be redefined between the covariance estimation and the EUR leakage calculation.
  2. The manuscript should include a short table comparing the key-consumption overhead of the standard EUR method versus the double-data modulation method for representative block sizes (e.g., 10^6 and 10^8).

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and the constructive comments on the double-data modulation scheme and the adapted parameter estimation. We address each major comment below and commit to revisions that strengthen the rigor of the presentation.

read point-by-point responses
  1. Referee: [Section describing double-data modulation (likely §4 or §5)] The central claim that reuse of the same data set for covariance-matrix estimation and max-entropy evaluation eliminates statistical fluctuations (Abstract) requires an explicit joint bound; the manuscript must derive how the estimator for the covariance matrix and the max-entropy term remain independent of the target secret-key rate when the identical quadrature data are shared, or show the additional finite-size correction term that appears.

    Authors: In the double-data modulation construction all transmitted quadrature values are retained and employed simultaneously for covariance-matrix estimation and for direct evaluation of the max-entropy term. Because the entire data set is used without any partitioning or subsampling step, the usual finite-size statistical fluctuation that would arise from estimating the max-entropy on a separate sample is absent by construction. We acknowledge that an explicit joint bound clarifying the statistical independence of the two estimators with respect to the final secret-key rate would improve clarity. We will therefore insert a short lemma (new Lemma 4.1) that derives the joint concentration inequality under shared data and confirms that no additional finite-size correction appears in the max-entropy term. revision: yes

  2. Referee: [Section on adapted parameter estimation under composable security] The adaptation of the parameter-estimation procedure to the composable EUR framework must be shown to avoid circularity: the covariance-matrix elements that enter the EUR bound are themselves estimated from the same data that determine the leakage term; an equation or lemma establishing that the resulting bound remains valid under this dependence is needed.

    Authors: The adapted finite-size covariance-matrix estimator is obtained from the same quadrature data that later enter the leakage term inside the EUR. The dependence is already accounted for in the composable-security analysis because the estimator is a deterministic function of the observed data and the security proof proceeds via a worst-case bound over all possible data realizations. Nevertheless, we agree that an explicit statement is desirable. We will add a short lemma (new Lemma 3.2) that shows the overall EUR bound remains valid under this data dependence by invoking the composable definition of the smooth min-entropy and the fact that the covariance-matrix estimator is Lipschitz-continuous in the observed quadratures. revision: yes

Circularity Check

0 steps flagged

No circularity in derivation chain

full rationale

The abstract and description present an adaptation of existing parameter estimation techniques to EUR analysis under composable security, plus a double-data modulation approach that reuses states. No equations, self-definitions, fitted inputs renamed as predictions, or load-bearing self-citations are exhibited that reduce any claimed result to its own inputs by construction. The work is therefore treated as self-contained against external benchmarks with no detected circular steps.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review yields no explicit free parameters, axioms, or invented entities; the central claims rest on unstated modeling assumptions typical of QKD security proofs such as Gaussian channel models and composable security definitions.

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Reference graph

Works this paper leans on

59 extracted references · 59 canonical work pages · 1 internal anchor

  1. [1]

    State preparation : Alice holds the squeezed states with squeezed variance VS before the pro- tocol begins, where VS ∈ (0, 1]. In every run of the protocol, Alice uses Gaussian random numbers xM to encode the displacement of quadratures by using modulators (generally containing amplitude and phase modulators), and the total modulation variance is denoted by VM

  2. [2]

    State transmission : Alice sends the modulated 3 state in the quantum channel, which is treated as a totally untrusted channel and controlled by Eve

  3. [3]

    Resulting from the fact that the practical measurement phase is always discrete, the ideal measurement outcomes should be discretized by the analogue-to-digital converter (ADC)

    State measurement : Bob receives the quantum state and randomly measures x or p quadrature by an ideal homodyne detector. Resulting from the fact that the practical measurement phase is always discrete, the ideal measurement outcomes should be discretized by the analogue-to-digital converter (ADC). The final discretized results are denoted by xB

  4. [4]

    Parameter estimation: Alice and Bob repeat the above steps many times until they have enough raw data (e.g., N ). Then, Alice or Bob reveals some of the raw data (with length m) through the classi- cal channel to estimate the key parameters of the channel, especially the data distance d0 between Alice’s and Bob’s data, the transmittance τ, and the excess ...

  5. [5]

    Error correction : According to the estimation parameters τ and ε, the communication parts esti- mate the leakage information ℓEC during the error correction phase and choose an appropriate classi- cal error reconciliation algorithm, e.g., low-density- parity-check (LDPC) code, to correct Alice’s error (in reverse reconciliation cases) or Bob’s error (in ...

  6. [6]

    data parameter

    Privacy amplification : Alice and Bob randomly choose a universal 2 hash function [ 45] and apply it to their respective keys to get the final private keys sA and sB with length ℓ, which are only known to themselves. Alice Eve Bob Hom ࢞۰ ܄ࡿS AM 0 11 0 0 0 0 0 0 11 0 1 0 0 11 0 0 0 0 0 0 11 0 1 0 ࢞ࡹ ADC PM ሻ Classical Channel Quantum Channel (Postprocessing)...

  7. [7]

    The covariance of xM and xB is: Cov (xM , x B) = √ τ VM =: cM B. (17) For obtaining the estimator of covariance ˆcM B, we also use Mi denoting the ith modulating value and Bi denot- ing the ith measurement result, for i = 1, 2, ..., m , respec- tively. According to the maximum likelihood estimation, we can get: ˆcM B = 1 m m∑ i=1 MiBi. (18) and it is easy...

  8. [8]

    Quantum cryptography

    Gisin, N.; Ribordy, G.; Tittel, W.; Zbinden, H. Quantum cryptography. Rev. Mod. Phys. 2002, 74, 145–195

  9. [9]

    The security of practical quantum key distribution

    Scarani, V.; Bechmann-Pasquinucci, H.; Cerf, N.J.; Duˇ sek, M.; L¨ utkenhaus, N.; Peev, M. The security of practical quantum key distribution. Rev. Mod. Phys. 2009, 81, 1301–1350

  10. [10]

    Gaussian quantum information

    Weedbrook, C.; Pirandola, S.; Garc ´ ıa-Patr´ on, R.; Cerf, N.J.; Ralph, T.C.; Shapiro, J.H.; Lloyd, S. Gaussian quantum information. Rev. Mod. Phys. 2012, 84, 621– 669

  11. [11]

    Distributing secret keys wi th quantum continuous variables: Principle, security and implementations

    Diamanti, E.; Leverrier, A. Distributing secret keys wi th quantum continuous variables: Principle, security and implementations. Entropy 2015, 17, 6072–6092

  12. [12]

    Advances in quantum cryptography

    Pirandola, S.; Andersen, U.L.; Banchi, L.; Berta, M.; Bunandar, D.; Colbeck, R.; Englund, D.; Gehring, T.; Lupo, C.; Ottaviani, C.; et al. Advances in quantum cryptography. arXiv 2019, arXiv:1906.01645

  13. [13]

    Continuous variable quantum cryptography

    Ralph, T.C. Continuous variable quantum cryptography. Phys. Rev. A 1999, 61, 010303(R)

  14. [14]

    Quantum cryptography with squeezed states

    Hillery, M. Quantum cryptography with squeezed states. Phys. Rev. A 2000, 61, 022309

  15. [15]

    Quantum distribu- tion of Gaussian keys using squeezed states

    Cerf, N.J.; L´ evy, M.; Van Assche, G. Quantum distribu- tion of Gaussian keys using squeezed states. Phys. Rev. A 2001, 63, 052311

  16. [16]

    Squeezed-state quantum key dis- tribution upon imperfect reconciliation

    Usenko, V.C.; Filip, R. Squeezed-state quantum key dis- tribution upon imperfect reconciliation. New J. Phys. 2011, 13, 113007

  17. [17]

    Grosshans, F.; Grangier, P.; Continuous variable quan - tum cryptography using coherent states. Phys. Rev. Lett. 2002, 88, 057902

  18. [18]

    Quantum key distribution using gaussian-modulated coherent states

    Grosshans, F.; van Assche, G.; Wenger, J.; Brouri, R.; Cerf, N.J.; Grangier, P. Quantum key distribution using gaussian-modulated coherent states. Nature 2003, 421, 238–241

  19. [19]

    Quantum cryptography without switching

    Weedbrook, C.; Lance, A.M.; Bowen, W.P.; Symul, T.; Ralph, T.C.; Lam, P.K. Quantum cryptography without switching. Phys. Rev. Lett. 2004, 93, 170504

  20. [20]

    Continuous-variable quantum cryptography using two- way quantum communication

    Pirandola, S.; Mancini, S.; Lloyd, S.; Braunstein, S.L . Continuous-variable quantum cryptography using two- way quantum communication. Nat. Phys. 2008, 4, 726– 730

  21. [21]

    Security of a new two-way continuous-variable quantum key distribution protocol

    Sun, M.; Peng, X.; Shen, Y.; Guo, H. Security of a new two-way continuous-variable quantum key distribution protocol. Int. J. Quantum Inf. 2012, 10, 1250059

  22. [22]

    Improvement of two-way continuous-variable quantum key distribution using op- tical amplifiers

    Zhang, Y.-C.; Li, Z.; Weedbrook, C.; Yu, S.; Gu, W.; Sun, M.; Peng, X.; Guo, H. Improvement of two-way continuous-variable quantum key distribution using op- tical amplifiers. J. Phys. B 2014, 47, 035501

  23. [23]

    Two-way Gaus - sian quantum cryptography against coherent attacks in direct reconciliation

    Ottaviani, C.; Mancini, S.; Pirandola, S. Two-way Gaus - sian quantum cryptography against coherent attacks in direct reconciliation. Phys. Rev. A 2015, 92, 062323

  24. [24]

    General immunity and su- peradditivity of two-way Gaussian quantum cryptogra- phy

    Ottaviani, C.; Pirandola, S. General immunity and su- peradditivity of two-way Gaussian quantum cryptogra- phy. Sci. Rep. 2016, 6, 22225

  25. [25]

    Numeri- cal simulation of the optimal two-mode attacks for two- way continuous-variable quantum cryptography in re- verse reconciliation

    Zhang, Y.; Li, Z.; Zhao, Y.; Yu, S.; Guo, H. Numeri- cal simulation of the optimal two-mode attacks for two- way continuous-variable quantum cryptography in re- verse reconciliation. J. Phys. B: At. Mol. Opt. Phys. 2017, 50, 035501

  26. [26]

    Unconditional security pr oof of long-distance continuous-variable quantum key distri- bution with discrete modulation

    Leverrier, A.; Grangier, P. Unconditional security pr oof of long-distance continuous-variable quantum key distri- bution with discrete modulation. Phys. Rev. Lett. 2009, 102, 180504

  27. [27]

    Continuous-variable quantum-key-distribution protocols with a non-Gaussian modulation

    Leverrier, A.; Grangier, P. Continuous-variable quantum-key-distribution protocols with a non-Gaussian modulation. Phys. Rev. A 2011, 83, 042312

  28. [28]

    User-defined quantum key distribution

    Li, Z.; Zhang, Y.; Guo, H. User-defined quantum key distribution. arXiv 2018, arXiv: 1805.04249

  29. [29]

    Continuous-variable measurement-device-independent quantum key distribution

    Li, Z.; Zhang, Y.-C.; Xu, F.; Peng, X.; Guo, H. Continuous-variable measurement-device-independent quantum key distribution. Phys. Rev. A 2014, 89, 052301

  30. [30]

    Continuous-variable measurement-device- independent quantum key distribution using squeezed states

    Zhang, Y.-C.; Li, Z.; Yu, S.; Gu, W.; Peng, X.; Guo, H. Continuous-variable measurement-device- independent quantum key distribution using squeezed states. Phys. Rev. A 2014, 90, 052325

  31. [31]

    High-rate measurement-device- independent quantum cryptography

    Pirandola, S.; Ottaviani, C.; Spedalieri, G.; Weedbro ok, C.; Braunstein, S.L.; Lloyd, S.; Gehring, T.; Jacob- sen, C.S.; Andersen, U.L. High-rate measurement-device- independent quantum cryptography. Nat. Photon. 2015, 9, 397–402

  32. [32]

    Finite-size analysis of continuous-variable measurement-device-independent quantum key distribu- tion

    Zhang, X.; Zhang, Y.; Zhao, Y.; Wang, X.; Yu, S.; Guo, H. Finite-size analysis of continuous-variable measurement-device-independent quantum key distribu- tion. Phys. Rev. A 2017, 96, 042334

  33. [33]

    Finit e- size analysis of measurement-device-independent quan- tum cryptography with continuous variables

    Papanastasiou, P.; Ottaviani, C.; Pirandola, S. Finit e- size analysis of measurement-device-independent quan- tum cryptography with continuous variables. Phys. Rev. A 2017, 96, 042332

  34. [34]

    Continuous-variable measurement-device- inde- pendent quantum key distribution: Composable security against coherent attacks

    Lupo, C.; Ottaviani, C.; Papanastasiou, P.; Piran- dola, S. Continuous-variable measurement-device- inde- pendent quantum key distribution: Composable security against coherent attacks. Phys. Rev. A 2018, 97, 052327

  35. [35]

    Composable security analysis of continuous-variable measurement-device-independent quantum key distribu- tion with squeezed states for coherent attacks

    Chen, Z.; Zhang, Y.; Wang, G.; Li, Z.; Guo, H. Composable security analysis of continuous-variable measurement-device-independent quantum key distribu- tion with squeezed states for coherent attacks. Phys. Rev. A 2018, 98, 012314

  36. [36]

    Field test of classical symmetric encryption with continuous vari- 10 ables quantum key distribution

    Jouguet, P.; Kunz-Jacques, S.; Debuisschert, T.; Fos- sier, S.; Diamanti, E.; All´ eaume, R.; Tualle-Brouri, R.; Grangier, P.; Leverrier, A.; Pache, P.; et al. Field test of classical symmetric encryption with continuous vari- 10 ables quantum key distribution. Opt. Express 2012, 20, 14030–14041

  37. [37]

    Experimental demonstration of long- distance continuous-variable quantum key distribution

    Jouguet, P.; Kunz-Jacques, S.; Leverrier, A.; Grangie r, P.; Diamanti, E. Experimental demonstration of long- distance continuous-variable quantum key distribution. Nat. Photon. 2013, 7, 378–381

  38. [38]

    Continuous-variable QKD over 50km commercial fiber

    Zhang, Y.; Li, Z.; Chen, Z.; Weedbrook, C.; Zhao, Y.; Wang, X.; Huang, Y.; Xu, C.; Zhang, X.; Wang, Z.; et al. Continuous-variable QKD over 50km commercial fiber. Quantum Sci. Technol. 2019, 4, 035006

  39. [39]

    Composable security proof for continuou s- variable quantum key distribution with coherent states

    Leverrier, A. Composable security proof for continuou s- variable quantum key distribution with coherent states. Phys. Rev. Lett. 2015, 114, 070501

  40. [40]

    Security of continuous-variable quantu m key distribution via a Gaussian de Finetti reduction

    Leverrier, A. Security of continuous-variable quantu m key distribution via a Gaussian de Finetti reduction. Phys. Rev. Lett. 2017, 118, 200501

  41. [41]

    Postselection t ech- nique for quantum channels with applications to quan- tum cryptography

    Christandl, M.; K¨ onig, R.; Renner,R. Postselection t ech- nique for quantum channels with applications to quan- tum cryptography. Phys. Rev. Lett. 2009, 102, 020504

  42. [42]

    Security of continuous-variable quantum key distribution against general attacks

    Leverrier, A.; Garc ´ ıa-Patr´ on, R.; Renner, R.; Cerf, N.J. Security of continuous-variable quantum key distribution against general attacks. Phys. Rev. Lett. 2013, 110, 030502

  43. [43]

    Continuous variable quantum key distribution: finite-key analysis of compos- able security against coherent attacks

    Furrer, F.; Franz, T.; Berta, M.; Leverrier, A.; Scholz , V.B.; Tomamichel, M.; Werner, R.F. Continuous variable quantum key distribution: finite-key analysis of compos- able security against coherent attacks. Phys. Rev. Lett. 2012, 109, 100502

  44. [44]

    Reverse-reconciliation continuous-varia ble quantum key distribution based on the uncertainty prin- ciple

    Furrer, F. Reverse-reconciliation continuous-varia ble quantum key distribution based on the uncertainty prin- ciple. Phys. Rev. A 2014, 90, 042325

  45. [45]

    Gehring, T.; H¨ andchen, V.; Duhme, J.; Furrer, F.; Franz, T.; Pacher, C.; Werner, R.F.; Schnabel. R. Implemen- tation of continuous-variable quantum key distribution with composable and one-sided-device-independent secu- rity against coherent attacks. Nat. Commun. 2015, 6, 8795

  46. [46]

    Source-dev ice- independent ultrafast quantum random number genera- tion

    Marangon, D.G.; Vallone,G.; Villoresi, P. Source-dev ice- independent ultrafast quantum random number genera- tion. Phy. Rev. Lett. 2017, 118, 060503

  47. [47]

    High speed continuous vari- able source-independent quantum random number gen- eration

    Xu, B.; Chen, Z.; Li, Z.; Yang, J.; Su, Q.; Huang, W.; Zhang, Y.; Guo, H. High speed continuous vari- able source-independent quantum random number gen- eration. Quantum Sci. Technol. 2019, 4, 025013

  48. [48]

    En- tropic uncertainty relations and their applications

    Coles, P.J.; Berta, M.; Tomamichel, M.; Wehner, S. En- tropic uncertainty relations and their applications. Rev. Mod. Phys. 2017, 89, 015002

  49. [49]

    Long-distance continuous-variable quantum key distribution with effi- cient channel estimation

    Ruppert, L.; Usenko, V.C.; Filip, R. Long-distance continuous-variable quantum key distribution with effi- cient channel estimation. Phys. Rev. A 2014, 90, 062310

  50. [50]

    Security of quantum key distribution

    Renner, R. Security of quantum key distribution. Ph.D. thesis, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Swiss, 2006

  51. [51]

    Composability in quantu m cryptography

    M¨ uller-Quade, J.; Renner, R. Composability in quantu m cryptography. New J. Phys. 2009, 11, 085006

  52. [52]

    Universal classes of hash functions

    Carter, J.L.; Wegman, M.N. Universal classes of hash functions. J. Comput. Syst. Sci. 1979, 18, 143

  53. [53]

    Composable se- curity of two-way continuous-variable quantum key dis- tribution without active symmetrization

    Ghorai, S.; Diamanti, E.; Leverrier, A. Composable se- curity of two-way continuous-variable quantum key dis- tribution without active symmetrization. Phys. Rev. A 2019, 99, 012311

  54. [54]

    Maximal violation of Bell in- equalities by position measurements

    Kiukas, J.; Werner, R.F. Maximal violation of Bell in- equalities by position measurements. J. Math. Phys. 2010, 51, 072105

  55. [55]

    Probability inequalities for the sum in s am- pling without replacement

    Serfling, R.J. Probability inequalities for the sum in s am- pling without replacement. Ann. Stat. 1974, 2, 39

  56. [56]

    Virtual entanglement and reconciliation pro- tocols for quantum cryptography with continuous vari- ables

    Grosshans, F.; Cerf, N.J.; Wenger, J.; Tualle-Brouri, R.; Grangier, P. Virtual entanglement and reconciliation pro- tocols for quantum cryptography with continuous vari- ables. Quantum Inf. Comput. 2003, 3, 535

  57. [57]

    13dB squeezed vacuum states at 1550nm from 12mW external pump power at 775nm

    Sch¨ onbeck, A.; Thies, F.; Schnabel, R. 13dB squeezed vacuum states at 1550nm from 12mW external pump power at 775nm. Opt. Lett. 2018, 43, 110

  58. [58]

    Quantum Inf

    Wang, X.; Zhang, Y.; Li, Z.; Xu, B.; Yu, S.; Guo, H.; Effi- cient rate-adaptive reconciliation for CV-QKD protocol. Quantum Inf. Comput. 2017, 17, 1123

  59. [59]

    High speed error correction for continuous-variable quantum key distribu- tion with multi-edge type LDPC code

    Wang, X.; Zhang, Y.; Yu, S.; Guo, H. High speed error correction for continuous-variable quantum key distribu- tion with multi-edge type LDPC code. Sci. Rep. 2018, 8, 10543