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Continuous-variable quantum key distribution protocols over noisy channels
Raul Garcia-Patron, Nicolas J. Cerf
TL;DR
Whether noise-enhanced robustness also appears in CV-QKD is complicated by the distinction between direct and reverse reconciliation. This paper introduces squeezed-state heterodyne detection and analyzes it through an equivalence with squeezed-state homodyne measurement supplemented by noisy post-processing. The resulting protocols attain the highest resistance to noise among Gaussian CV-QKD protocols, with Bob’s added noise tuned for each channel.
Problem
Whether noise-enhanced robustness also appears in CV-QKD is unclear because the distinction between direct and reverse reconciliation makes the effect nonstraightforward to identify.
Source: p. 1Method
The paper introduces squeezed-state heterodyne detection and analyzes its equivalence to squeezed-state homodyne measurement supplemented with noisy post-processing.
Source: p. 1Results
The resulting protocol family has the highest resistance to noise among Gaussian CV-QKD protocols, with an optimal Bob-added noise level for each channel.
Source: p. 4Takeaways & Limitations
Noise-enhanced tolerance provides a physical explanation for previously poorly understood differences between the efficiencies of Gaussian protocols.
Source: p. 4The analysis focuses on collective Gaussian attacks and takes as a conjecture that collective-attack security suffices for unconditional security in CV-QKD.
Source: pp. 1–2
Abstract
from arXiv · showhide
A continuous-variable quantum key distribution protocol based on squeezed states and heterodyne detection is introduced and shown to attain higher secret key rates over a noisy line than any other one-way Gaussian protocol. This increased resistance to channel noise can be understood as resulting from purposely adding noise to the signal that is converted into the secret key. This notion of noise-enhanced tolerance to noise also provides a better physical insight into the poorly understood discrepancies between the previously defined families of Gaussian protocols.