Fig. 3: Quantum Fisher information normalized by the ultimate limit \({{{{\mathcal{J}}}}}_{{{{\rm{UB}}}}}\).
From: Ultimate precision limit of noise sensing and dark matter search
a Squeezed vacuum, \({{{{\mathcal{J}}}}}_{{{{\rm{SV}}}}}/{{{{\mathcal{J}}}}}_{{{{\rm{UB}}}}}\); b TMSV sources, \({{{{\mathcal{J}}}}}_{{{{\rm{TMSV}}}}}/{{{{\mathcal{J}}}}}_{{{{\rm{UB}}}}}\). Cyan dashed: \({{{{\mathcal{J}}}}}_{{{{\rm{UB,UE}}}}}={{{{\mathcal{J}}}}}_{{{{\rm{UB,TP}}}}}\); \({{{{\mathcal{J}}}}}_{{{{\rm{UB,UE}}}}} > {{{{\mathcal{J}}}}}_{{{{\rm{UB,TP}}}}}\) for larger G, namely one adopts \({{{{\mathcal{J}}}}}_{{{{\rm{UB}}}}}={{{{\mathcal{J}}}}}_{{{{\rm{UB,TP}}}}}\) above the cyan line, \({{{{\mathcal{J}}}}}_{{{{\rm{UB}}}}}={{{{\mathcal{J}}}}}_{{{{\rm{UB,UE}}}}}\) otherwise. The values of maximum and minimum in each subplot are highlighted in red. The range between the adjacent two contours is 0.1. nB = 10−3. As a reminder, \(G={e}^{2r}=\exp \{2{\sinh }^{-1}\sqrt{{N}_{{{\rm{S}}}}}\}\).
