Improvement of phase sensitivity in SU(1,1) interferometer using number-conserving operations.

We propose a theoretical scheme to improve the phase sensitivity by introducing the number-conserving generalized superposition of product into squeezed thermal state of the traditional SU(1,1) interferometer with intensity detection. We investigate the effect of different parameter and photon losses on phase sensitivity under the condition of the ideal and the realistic phase estimation process, respectively. Moreover, compared with the previous methods, our scheme can not only enhance the phase sensitivity, but also significantly suppress the photon losses with only first-order GSP operation. It means that our scheme needs less resources and less operations to obtain higher phase sensitivity. These above results indicate that our scheme is viable in the phase sensitivity improvement, which may have practical applications in quantum information processing. • In the actual production process of the squeezed state light field, STS instead of the pure SVS may be generated due to some unavoidable losses and extra noise. • A novel non-Gaussian operation, the number-conserving generalized superposition of products (GSP) operation is applied on squeezed thermal state (STS) to further enhance the sensitivity of the phase estimation. • In addition, we shall compare the effects of different non-Gaussian operations on phase sensitivity, including PSA, PAS, as well as general generalized superposition. [ABSTRACT FROM AUTHOR]