The Phase Sensitivities for Different Phase-Shift Configurations in an SU(1,1) Interferometer*

Fan Wang,Wei Zhong,Lan Zhou,Yu-Bo Sheng

Fig. 1 (Color online) SU(1,1) interferometer model with two types of phase shift: one-arm and two-arm. The input state is $|\alpha\rangle\otimes|\xi\rangle$. After the first OPA, it accumulates an unknown phase, which is determinated by $U_{\theta}$. Then it goes through the second OPA and a homodyne measurement is performed. The pump field between the two OPAs has a $\pi$ phase difference.