Quantum interferometer with two-mode squeezed vacuum：Ŝ_z² measurement

Quantum interferometric strategy with input two-mode squeezed vacuum Phys. Rev. Lett. 104 103602 is reexamined for both parity and Ŝ_z² measurements. Unlike the previous scheme, we find that phase sensitivity obtained with the Ŝ_z² measurement is minimized at phase origin, which may be useful to estimate a small phase shift at high precision. For the phase deviated from zero, the sensitivity increases more slowly than that of the parity detection.