Negativity of Wigner function and phase sensitivity of an SU(1,1) interferometer
Liu Chun-Li, Guo Li-Li, Zhang Zhi-Ming †, Yu Ya-Fei ‡
       

Schematic diagram of an SU(1,1)I. Wi and Wf correspond to Wigner functions of input and output fields. g 1 ( 2 ) and θ 1 ( 2 ) describe the strength and the phase shift in the OPA process 1(2), respectively.