Fig. 2: Min-entropy versus the conditional quantum signal-to-noise ratio.
From: Homodyne-based quantum random number generator at 2.9 Gbps secure against quantum side-information
Min-entropy for 8-, 12-, and 16-bit analog-to-digital converter (ADC) resolution versus the ratio of conditional variance of the vacuum fluctuations and the conditional variance of the excess noise, \(({\sigma }_{X}^{2}-{\sigma }_{U}^{2})/{\sigma }_{U}^{2}\). Here \({\sigma }_{X}^{2}\) and \({\sigma }_{U}^{2}\) are the conditional variance of the measurement outcomes and of the excess noise, respectively. The shaded areas indicate the regions between low correlations (\({\sigma }_{X}^{2}/{\sigma }^{2}=0.99\)), upper trace and high correlations (\({\sigma }_{X}^{2}/{\sigma }^{2}=0.1\)), lower trace. Thereby σ2 is the variance of the measurement outcomes, which has been optimized to obtain the highest min-entropy. The ADC is assumed to be ideal without digitization errors.
