Publications associated with Optical Quantum Technologies

Quantum phase estimation with lossy interferometers

Physical Review A - Atomic, Molecular, and Optical Physics 80 (2009)

R Demkowicz-Dobrzanski, U Dorner, BJ Smith, JS Lundeen, W Wasilewski, K Banaszek, IA Walmsley

We give a detailed discussion of optimal quantum states for optical two-mode interferometry in the presence of photon losses. We derive analytical formulae for the precision of phase estimation obtainable using quantum states of light with a definite photon number and prove that maximization of the precision is a convex optimization problem. The corresponding optimal precision, i.e., the lowest possible uncertainty, is shown to beat the standard quantum limit thus outperforming classical interferometry. Furthermore, we discuss more general inputs: states with indefinite photon number and states with photons distributed between distinguishable time bins. We prove that neither of these is helpful in improving phase estimation precision. © 2009 The American Physical Society.

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