Sub-Shot-Noise Quantum Optical Interferometry: A Comparison of Entangled State Performance within a Unified Measurement Scheme

TL;DR

This paper demonstrates that parity measurement enables reaching the Heisenberg limit in phase sensitivity across various entangled states in quantum optical interferometry, simplifying measurement schemes and analyzing loss effects.

Contribution

It introduces a unified parity measurement scheme that achieves the Heisenberg limit for different entangled states in quantum interferometry.

Findings

Parity measurement attains Heisenberg limit for multiple entangled states.

Photon loss reduces phase sensitivity, with effects analyzed for each state.

Unified measurement scheme simplifies quantum interferometry implementations.

Abstract

Phase measurement using a lossless Mach-Zehnder interferometer with certain entangled $N$-photon states can lead to a phase sensitivity of the order of 1/N, the Heisenberg limit. However, previously considered output measurement schemes are different for different input states to achieve this limit. We show that it is possible to achieve this limit just by the parity measurement for all the commonly proposed entangled states. Based on the parity measurement scheme, the reductions of the phase sensitivity in the presence of photon loss are examined for the various input states.