Implementation of continuous variable quantum cryptography in optical fibres using a go-&-return configuration

2006 ◽  
Vol 6 (4&5) ◽  
pp. 326-335
Author(s):  
M. Legré ◽  
H. Zbinden ◽  
N. Gisin
Keyword(s):  
Quantum Cryptography ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variable ◽  
Optical Fibres ◽  
Continuous Variables ◽  
Phase Fluctuations ◽  
Degree Of Stability ◽  
Set Up ◽  
High Degree

We demonstrate an implementation of quantum key distribution with continuous variables based on a go-&-return configuration over distances up to 14km. This configuration leads to self-compensation of polarisation and phase fluctuations. We observe a high degree of stability of our set-up over many hours.

scholarly journals CONTINUOUS VARIABLE QUANTUM KEY DISTRIBUTION USING POLARIZED COHERENT STATES

2006 ◽  
Vol 20 (11n13) ◽  
pp. 1287-1296 ◽  
Author(s):  
A. VIDIELLA-BARRANCO ◽  
L. F. M. BORELLI
Keyword(s):  
Quantum Key Distribution ◽  
Coherent States ◽  
Key Distribution ◽  
Continuous Variable ◽  
Stokes Parameters ◽  
Continuous Variables ◽  
Commuting Operators ◽  
Incoming Beam ◽  
Ideal Situation ◽  
Quantum Counterpart

We discuss a continuous variables method of quantum key distribution employing strongly polarized coherent states of light. The key encoding is performed using the variables known as Stokes parameters, rather than the field quadratures. Their quantum counterpart, the Stokes operators Ŝi ( i =1,2,3), constitute a set of non-commuting operators, being the precision of simultaneous measurements of a pair of them limited by an uncertainty-like relation. Alice transmits a conveniently modulated two-mode coherent state, and Bob randomly measures one of the Stokes parameters of the incoming beam. After performing reconciliation and privacy amplification procedures, it is possible to distill a secret common key. We also consider a non-ideal situation, in which coherent states with thermal noise, instead of pure coherent states, are used for encoding.

scholarly journals Impact of receiver imbalances on the security of continuous variables quantum key distribution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Daniel Pereira ◽  
Margarida Almeida ◽  
Margarida Facão ◽  
Armando N. Pinto ◽  
Nuno A. Silva
Keyword(s):  
Communication Network ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variable ◽  
Continuous Variables ◽  
Security Risk ◽  
Channel Parameters ◽  
The Impact

AbstractContinuous-variable quantum key distribution (CV-QKD) provides a theoretical unconditionally secure solution to distribute symmetric keys among users in a communication network. However, the practical devices used to implement these systems are intrinsically imperfect, and, as a result, open the door to eavesdropper attacks. In this work, we show the impact of receiver device imperfections on the estimated channel parameters, performance and security of a CV-QKD system. The presented results show that, due to the erroneously estimated channel parameters, non-monitored imbalances can pose a security risk or even reduce the system’s performance. Our results show the importance of monitoring these imbalances and hint at the possibility of compensating for some receiver imbalances by tuning other components.

scholarly journals Improving Eight-State Continuous Variable Quantum Key Distribution by Applying Photon Subtraction

2019 ◽  
Vol 9 (7) ◽  
pp. 1333 ◽  
Author(s):  
Qingquan Peng ◽  
Xiaodong Wu ◽  
Ying Guo
Keyword(s):  
Quantum Key Distribution ◽  
Single Photon ◽  
Key Distribution ◽  
Continuous Variable ◽  
Quantum States ◽  
Continuous Variables ◽  
Subtraction Method ◽  
Photon Subtraction ◽  
Channel Loss ◽  
Simulation Results

We propose a new method to effectively improve the performance of a quantum key distribution with eight-state continuous variables by the photon subtraction method. This operation is effective in increasing and distilling Gaussian entanglement between quantum states, and can be easily realized by existing technology. Simulation results show that the channel-loss tolerance of the eight-state continuous variable quantum key distribution (CVQKD) protocol can be extended by the appropriate photon subtraction algorithm; namely, single-photon subtraction.

Quantum key distribution over 25 km using a fibre set-up based on continuous variables

2007 ◽  
Vol 32 (2-3) ◽  
pp. 163-165
Author(s):  
J. Lodewyck ◽  
M. Bloch ◽  
S. Fossier ◽  
E. Diamanti ◽  
T. Debuisschert ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variables ◽  
Set Up

scholarly journals Secret Key Rate Adaption for Multicarrier Continuous-Variable Quantum Key Distribution

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Laszlo Gyongyosi ◽  
Sandor Imre
Keyword(s):  
Error Rate ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variable ◽  
Continuous Variables ◽  
Secret Key ◽  
Computational Tools ◽  
Minimal Error ◽  
Iterative Error

Abstract A multicarrier continuous-variable quantum key distribution (CVQKD) protocol uses Gaussian subcarrier quantum continuous variables (CVs) for the transmission. Here, we define an iterative error-minimizing secret key adaption method for multicarrier CVQKD. The proposed method allows for the parties to reach a given target secret key rate with minimized error rate through the Gaussian sub-channels by a sub-channel adaption procedure. The adaption algorithm iteratively determines the optimal transmit conditions to achieve the target secret key rate and the minimal error rate over the sub-channels. The solution requires no complex calculations or computational tools, allowing for easy implementation for experimental scenarios.

scholarly journals Implementation of Authenticated Hybrid QKD Protocols for 802.11 LANs

2020 ◽  
Vol 9 (4) ◽  
pp. 2663-2669
Keyword(s):  
Quantum Cryptography ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Session Key ◽  
Two Phases ◽  
Set Up

Quantum cryptography (QC) is used to give approved secure correspondence between the sender and beneficiary. In QC, Authentication Hybrid Quantum Key Distribution Protocols (AHQKDPs) use quantum segments to isolate session keys and open talks to check for covert operatives and affirm the rightness of a session key. In any case, open talks require additional correspondence adjusts between sender beneficiaries. The benefit of QC adequately is against replay and inert assaults. An AQKDP with certain customer approval, which ensures that protection, is achievable for valid down customers and the mutual check is practiced carefully when secure correspondence using the session key starts. AQKDP have two phases, for instance, set up the stage and the appropriation stage to give 3, parties QKDP. In this system, there is no basic perception between the sender and beneficiary. Both sender and beneficiary must focus on confided in core interest. In this express, check blend AHQKDP has two phases, for instance, set up the stage and the dispersion stage to give three gatherings affirmations, and secure session key appointment. In this structure, there is basic perception between the sender and beneficiary. Both sender and beneficiary must compare direct with approval of confided in core interest

scholarly journals An FPGA-Based LDPC Decoder With Ultra-Long Codes for Continuous-Variable Quantum Key Distribution

IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 47687-47697
Author(s):  
Shen-Shen Yang ◽  
Jian-Qiang Liu ◽  
Zhen-Guo Lu ◽  
Zeng-Liang Bai ◽  
Xu-Yang Wang ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variable ◽  
Ldpc Decoder

scholarly journals A novel error correction protocol for continuous variable quantum key distribution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kadir Gümüş ◽  
Tobias A. Eriksson ◽  
Masahiro Takeoka ◽  
Mikio Fujiwara ◽  
Masahide Sasaki ◽  
...  
Keyword(s):  
Error Correction ◽  
Quantum Key Distribution ◽  
Ldpc Codes ◽  
Key Distribution ◽  
Continuous Variable ◽  
Early Termination ◽  
Parity Check ◽  
Secret Key ◽  
Ldpc Decoder ◽  
And Performance

AbstractReconciliation is a key element of continuous-variable quantum key distribution (CV-QKD) protocols, affecting both the complexity and performance of the entire system. During the reconciliation protocol, error correction is typically performed using low-density parity-check (LDPC) codes with a single decoding attempt. In this paper, we propose a modification to a conventional reconciliation protocol used in four-state protocol CV-QKD systems called the multiple decoding attempts (MDA) protocol. MDA uses multiple decoding attempts with LDPC codes, each attempt having fewer decoding iteration than the conventional protocol. Between each decoding attempt we propose to reveal information bits, which effectively lowers the code rate. MDA is shown to outperform the conventional protocol in regards to the secret key rate (SKR). A 10% decrease in frame error rate and an 8.5% increase in SKR are reported in this paper. A simple early termination for the LDPC decoder is also proposed and implemented. With early termination, MDA has decoding complexity similar to the conventional protocol while having an improved SKR.

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