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arXiv · 1609.04689

Adaptive phase estimation with two-mode squeezed-vacuum and parity measurement

Zixin Huang·Keith R. Motes·Petr M. Anisimov·Jonathan P. Dowling·Dominic W. Berry
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Abstract

A proposed phase-estimation protocol based on measuring the parity of a two-mode squeezed-vacuum state at the output of a Mach-Zehnder interferometer shows that the Cramér-Rao sensitivity is sub-Heisenberg [Phys.\ Rev.\ Lett.\ {\bf104}, 103602 (2010)]. However, these measurements are problematic, making it unclear if this sensitivity can be obtained with a finite number of measurements. This sensitivity is only for phase near zero, and in this region there is a problem with ambiguity because measurements cannot distinguish the sign of the phase. Here, we consider a finite number of parity measurements, and show that an adaptive technique gives a highly accurate phase estimate regardless of the phase. We show that the Heisenberg limit is reachable, where the number of trials needed for mean photon number $\bar{n}=1$ is approximately one hundred. We show that the Cramér-Rao sensitivity can be achieved approximately, and the estimation is unambiguous in the interval ($-π/2, π/2$).

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Zixin Huang, Keith R. Motes, Petr M. Anisimov, Jonathan P. Dowling, Dominic W. Berry. 2016-09-15. Adaptive phase estimation with two-mode squeezed-vacuum and parity measurement. https://doi.org/10.1103/physreva.95.053837

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