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We study the effect of losses on the phase sensitivity of the SU (1, 1) interferometer for different configurations. We find that this type of interferometer is robust against losses that result from an inefficient detection system. This type of loss only introduces an overall prefactor to the sensitivity but does not change the 1/n scaling, where n is the average number of particles inside the interferometer, characteristic of the Heisenberg limit. In addition, we show that under some conditions the SU (1, 1) interferometer with coherent state inputs is also robust against internal losses. These results show that the SU (1, 1) interferometer is a viable candidate for experimentally reaching the Heisenberg limit with current technology. Possible implementations of this interferometer using four-wave mixing in atomic vapors or an atom interferometer in a spinor Bose-Einstein condensate are compared.
Marino et al. (Fri,) studied this question.