Quantum interferometer with two-mode squeezed vacuum: Ŝ 2 z measurement

Quantum interferometric strategy with input two-mode squeezed vacuum [Phys. Rev. Lett. 104 103602] is reexamined for both parity and Ŝ2z measurements. Unlike the previous scheme, we find that phase sensitivity obtained with the Ŝ2z 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.