scholarly journals Long-distance continuous-variable quantum key distribution by controlling excess noise

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Duan Huang ◽  
Peng Huang ◽  
Dakai Lin ◽  
Guihua Zeng

Entropy ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 55
Author(s):  
Ivan Derkach ◽  
Vladyslav C. Usenko

We address the applicability of quantum key distribution with continuous-variable coherent and squeezed states over long-distance satellite-based links, considering low Earth orbits and taking into account strong varying channel attenuation, atmospheric turbulence and finite data ensemble size effects. We obtain tight security bounds on the untrusted excess noise on the channel output, which suggest that substantial efforts aimed at setup stabilization and reduction of noise and loss are required, or the protocols can be realistically implemented over satellite links once either individual or passive collective attacks are assumed. Furthermore, splitting the satellite pass into discrete segments and extracting the key from each rather than from the overall single pass allows one to effectively improve robustness against the untrusted channel noise and establish a secure key under active collective attacks. We show that feasible amounts of optimized signal squeezing can substantially improve the applicability of the protocols allowing for lower system clock rates and aperture sizes and resulting in higher robustness against channel attenuation and noise compared to the coherent-state protocol.



2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shengjun Ren ◽  
Shuai Yang ◽  
Adrian Wonfor ◽  
Ian White ◽  
Richard Penty

AbstractWe present an experimental demonstration of the feasibility of the first 20 + Mb/s Gaussian modulated coherent state continuous variable quantum key distribution system with a locally generated local oscillator at the receiver (LLO-CVQKD). To increase the signal repetition rate, and hence the potential secure key rate, we equip our system with high-performance, wideband devices and design the components to support high repetition rate operation. We have successfully trialed the signal repetition rate as high as 500 MHz. To reduce the system complexity and correct for any phase shift during transmission, reference pulses are interleaved with quantum signals at Alice. Customized monitoring software has been developed, allowing all parameters to be controlled in real-time without any physical setup modification. We introduce a system-level noise model analysis at high bandwidth and propose a new ‘combined-optimization’ technique to optimize system parameters simultaneously to high precision. We use the measured excess noise, to predict that the system is capable of realizing a record 26.9 Mb/s key generation in the asymptotic regime over a 15 km signal mode fibre. We further demonstrate the potential for an even faster implementation.





2020 ◽  
Vol 125 (1) ◽  
Author(s):  
Yichen Zhang ◽  
Ziyang Chen ◽  
Stefano Pirandola ◽  
Xiangyu Wang ◽  
Chao Zhou ◽  
...  


2020 ◽  
Vol 26 (3) ◽  
pp. 1-12 ◽  
Author(s):  
Masoud Ghalaii ◽  
Carlo Ottaviani ◽  
Rupesh Kumar ◽  
Stefano Pirandola ◽  
Mohsen Razavi


2011 ◽  
Vol 84 (6) ◽  
Author(s):  
Paul Jouguet ◽  
Sébastien Kunz-Jacques ◽  
Anthony Leverrier


2012 ◽  
Vol 10 (05) ◽  
pp. 1250059 ◽  
Author(s):  
MAOZHU SUN ◽  
XIANG PENG ◽  
YUJIE SHEN ◽  
HONG GUO

The original two-way continuous-variable quantum-key-distribution (CV-QKD) protocols [S. Pirandola, S. Mancini, S. Lloyd and S. L. Braunstein, Nat. Phys. 4 (2008) 726] give the security against the collective attack on the condition of the tomography of the quantum channels. We propose a family of new two-way CV-QKD protocols and prove their security against collective entangling cloner attacks without the tomography of the quantum channels. The simulation result indicates that the new protocols maintain the same advantage as the original two-way protocols whose tolerable excess noise surpasses that of the one-way CV-QKD protocol. We also show that all sub-protocols within the family have higher secret key rate and much longer transmission distance than the one-way CV-QKD protocol for the noisy channel.





2013 ◽  
Vol 7 (5) ◽  
pp. 378-381 ◽  
Author(s):  
Paul Jouguet ◽  
Sébastien Kunz-Jacques ◽  
Anthony Leverrier ◽  
Philippe Grangier ◽  
Eleni Diamanti


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