# The Rationale for the Optimal Continuous-Variable Quantum Key Distribution Protocol

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Classification of CV-QKD Protocols and Justification of Optimal Parameters

#### 2.1. General Approach to CV-QKD Protocol Description

#### 2.2. Quantum Channel Implementation

#### 2.3. Channel Configuration Schemes

#### 2.4. Types of Modulation

#### 2.5. Quantum States

#### 2.6. Coherent Detection Schemes

#### 2.6.1. Homodyne Detection

#### 2.6.2. Heterodyne Detection

#### 2.6.3. Heterodyne Detection with Transfer to Difference Frequency

#### 2.6.4. Coherent Detection and Protocol Security

#### 2.7. Types of LO

- Eve introduces an attenuator featuring an attenuation coefficient $0\le \alpha \le 1$ into the channel for a fraction $0\le \nu \le 1$ of LO pulses to change the shape of the pulses themselves. The trigger is delayed by $\delta $.
- Eve introduces a beam splitter featuring a transmission coefficient $0\le \mu \le 1$ and realizes an attack as a partial “intercept-resend” [74]. Thus, the excess noise of the system is given by:$${\xi}_{a}=\xi +2\mu {N}_{0},$$

#### 2.8. Reconciliation Protocols

## 3. Conclusions

- General scheme of the protocol—PM scenario;
- Quantum channel implementation—fiber-optical network;
- Channel configuration—one-way scheme;
- Type of modulation—Gaussian modulation;
- Signal states—single-mode coherent states;
- Coherent detection scheme—heterodyning;
- LO implementation—on Alice’s side;
- Reconciliation protocol—reverse reconciliation.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Acknowledgments

## Conflicts of Interest

## References

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Classification | Item |
---|---|

general scheme of a protocol | prepare-and-measure; entanglement-based |

quantum channel implementation | fiber-optical; free space |

channel configuration | one-way scheme; two-way scheme |

type of modulation | Gaussian; non-Gaussian |

signal states | single-mode squeezed; single-mode coherent; multimode coherent; two-mode squeezed; thermal |

coherent detection schemes | homodyne; heterodyne (double homodyne); heterodyne at intermediate frequency |

LO implementation | on Alice’s side; on Bob’s side |

reconciliation protocols | direct (or forward); reverse |

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**MDPI and ACS Style**

Goncharov, R.; Vorontsova, I.; Kirichenko, D.; Filipov, I.; Adam, I.; Chistiakov, V.; Smirnov, S.; Nasedkin, B.; Pervushin, B.; Kargina, D.;
et al. The Rationale for the Optimal Continuous-Variable Quantum Key Distribution Protocol. *Optics* **2022**, *3*, 338-351.
https://doi.org/10.3390/opt3040030

**AMA Style**

Goncharov R, Vorontsova I, Kirichenko D, Filipov I, Adam I, Chistiakov V, Smirnov S, Nasedkin B, Pervushin B, Kargina D,
et al. The Rationale for the Optimal Continuous-Variable Quantum Key Distribution Protocol. *Optics*. 2022; 3(4):338-351.
https://doi.org/10.3390/opt3040030

**Chicago/Turabian Style**

Goncharov, Roman, Irina Vorontsova, Daniil Kirichenko, Ilya Filipov, Iurii Adam, Vladimir Chistiakov, Semyon Smirnov, Boris Nasedkin, Boris Pervushin, Daria Kargina,
and et al. 2022. "The Rationale for the Optimal Continuous-Variable Quantum Key Distribution Protocol" *Optics* 3, no. 4: 338-351.
https://doi.org/10.3390/opt3040030