Fig. 1. Curves give uncertainty in S^1 and 4(ΔS^1)2 as a function of T(=TV/TH). The dashed line corresponds to the desired pure state, while the solid curves represent the mixed states with background terms taken into consideration. Different colors means different percentages of the desired state in the mixed state. The points represent Shalm’s experimental data^[18].

Fig. 2. Curves give δCRB as a function of T. The red line corresponds to the desired pure state, while the blue one corresponds to the mixed state after considering background terms, when λ1=0.5. The two filled dots represent the minimums of the two curves.