Quantum correlations in optical metrology: Heisenberg-limited phase estimation without mode entanglement

Abstract

The quantum fisher information and quantum correlation parameters are employed to study the application of non-classical light to the problem of parameter estimation. It is shown that the optimal measurement sensitivity of a quantum state is determined by its inter-mode correlations (which depends of path-entanglement) and intra-mode correlations (which depends of the photon statistics). In light of these results, we consider the performance of quantum-enhanced optical interferometers. Furthermore, we propose a Heisenberg-limited metrology protocol involving standard elements from passive and active linear optics, for which the quantum Cramér-Rao bound is saturated with an intensity measurement. Interestingly, the quantum advantage for this scheme is derived solely from the non-classical photon statistics of the probe state and does not depend of entanglement. We study the performance of this scheme in the presence of realistic losses and consequently predict a substantial enhancement over the shot-noise limit with current technological capabilities.

8 pages, 3 figures, 1 table

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Cited by in corpus (4)

• Phase sensitivity of gain-unbalanced nonlinear interferometers
• Non-asymptotic analysis of quantum metrology protocols beyond the Cramér-Rao bound
• Quantum Fisher information maximization in an unbalanced interferometer
• Correlations for subsets of particles in symmetric states: what photons are doing within a beam of light when the rest are ignored