Phase Sensitivity of a Multi-mode Nonlinear Interferometer with Single Photons.

We propose a multi-mode nonlinear interferometer and study its phase sensitivity for two, three and four modes with single photons as inputs. We find that the phase sensitivity of the nonlinear interferometers can be improved by increasing the nonlinear index k. And when the total number of the input photons is fixed, increasing the number of modes is detrimental to the phase sensitivity. [ABSTRACT FROM AUTHOR]