In the Gaussian-modulated coherent states (GMCS) quantum key distribution (QKD), basis choice is a necessary procedure if homodyne detector is used. However, finite bandwidth of the digital-to-analog convertor (DAC) at the receiver’s side may lead to the imperfection of the basis choice, namely, maybe Bob can not exactly modulate 0 or ##IMG## [http://ej.iop.org/images/1612-202X/17/5/055203/lplab7eb7ieqn1.gif] {$\frac{\pi}{2}$} on the phase modulator to implement the homodyne detection.We investigate the GMCS QKD scheme with imperfect basis choice under realistic conditions of quantum channel and detector.We show that the imperfection causes a misestimate of the transmittance and the excess noise, the secret key rate and the security of the system are dramatically decreased consequently. To achieve a reliable quantum key distribution, a security bound to the noise induced by the imperfect basis choice is derived for reverse reconciliation and homodyne detect...

中文翻译：

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连续变量量子密钥分配中不完善的基础选择

在高斯调制相干态（GMCS）量子密钥分配（QKD）中，如果使用零差检测器，则基础选择是必要的过程。但是，接收器一侧的数模转换器（DAC）的有限带宽可能会导致基准选择的不完善，即，鲍勃可能无法精确调制0或## IMG ## [http：// ej .iop.org / images / 1612-202X / 17/5/055203 / lplab7eb7ieqn1.gif] {$ \ frac {\ pi} {2} $}在相位调制器上实现零差检测。我们研究了GMCS QKD方案结果表明，缺陷会导致对透射率的误估计，并且会产生过多的噪声，从而显着降低了秘密密钥的使用率和系统的安全性。为了实现可靠的量子密钥分配，