Accurate phase measurement with classical light

TL;DR

This paper demonstrates that classical light can achieve phase measurement precision comparable to NOON-states in multiphoton detection processes, challenging the notion that entanglement is necessary for optimal phase estimation.

Contribution

It shows that classical light can replace entangled states in certain quantum measurement schemes, achieving similar phase variance scaling.

Findings

Classical light achieves the same multiphoton detection probability as NOON-states.

Optimal phase variance with classical light scales identically to that with NOON-states.

Classical light does not hinder multiphoton absorption rates in the proposed scheme.

Abstract

In this paper we investigate whether it is in general possible to substitute maximally path-entangled states, namely NOON-states by classical light in a Doppleron-type resonant multiphoton detection processes by studying adaptive phase measurement with classical light. We show that multiphoton detection probability using classical light coincides with that of NOON-states and the multiphoton absorbtion rate is not hindered by the spatially unconstrained photons of the classical light in our scheme. We prove that the optimal phase variance with classical light can be achieved and scales the same as that using NOON-states.