We propose the Gaussian continuous-variable quantum key distribution using squeezed states in the composite channels including atmospheric propagation with transmittance fluctuations. We show that adjustments of signal modulation and use of optimal feasible squeezing can be sufficient to significantly overcome the coherent-state protocol and drastically improve the performance of quantum key distribution in atmospheric channels, also in the presence of additional attenuating and noisy channels. Furthermore, we consider examples of atmospheric links of different lengths, and show that optimization of both squeezing and modulation is crucial for reduction of protocol downtime and increase of secure atmospheric channel distance. Our results demonstrate unexpected advantage of fragile squeezed states of light in the free-space quantum key distribution applicable in daylight and stable against atmospheric turbulence.

中文翻译：

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压缩增强的量子密钥分布在大气通道上

我们提出了在复合通道中使用压缩状态的高斯连续可变量子密钥分布，包括具有透射率波动的大气传播。我们表明，信号调制的调整和最佳可行压缩的使用足以显着克服相干状态协议并显着提高大气通道中量子密钥分配的性能，即使存在额外的衰减和噪声通道。此外，我们考虑了不同长度的大气链路的例子，并表明压缩和调制的优化对于减少协议停机时间和增加安全大气信道距离至关重要。