Supersensitivity of Kerr phase estimation with two-mode squeezed vaccum states

We analytically investigate the sensitivity of Kerr nonlinear phase estimation in a Mach-Zehnder interferometer with two-mode squeezed vacuum states. We find that such a metrological scheme could access a sensitivity scaling over the Boixo et al.'s generalized sensitivity limit [S. Boixo et al., Phys. Rev. Lett. 98, 090401 (2007)], which is saturable with celebrated NOON states. We also show that parity detection is a quasi-optimal measurement which can nearly saturate the quantum Cramer-Rao bound in the aforementioned situation.