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Heisenberg limited phase estimation with mode-entangled coherent states

Anil Shaji, The University of New Mexico

(Session 7 : Saturday from 1:00-1:30)

Abstract. We investigate phase estimation in a Mach-Zehnder type interferometer using the ``0BB0" state which is a mode-entangled state formed by superposing a state with the vacuum in the first arm of the interferometer and a coherent state in the second arm and another state with the coherent state in the first arm and the vacuum in the second. The quantum Cramer-Rao bound on the measurement uncertainty in the estimate of an unknown phase shift between the two arms of the interferometer scales inversely with the mean photon number in the 0BB0 state (Heisenberg limited scaling). We discuss how 0BB0 states can be created and also the measurements that must be performed on the output state of the interferometer in order to find the phase shift. We compare the performance of the 0BB0 states in phase estimation with that of ``N00N" states. In the presence of photon loss, using 0BB0 states instead of N00N states, lead to lower measurement uncertainties.