Strategies for choosing path-entangled number states for optimal robust quantum optical metrology in the presence of loss

TL;DR

This paper investigates how to select optimal path-entangled Fock states for robust quantum optical metrology under loss, demonstrating that different states perform better depending on the loss level and achieving sub-shot-noise sensitivity.

Contribution

The study provides a strategy for choosing path-entangled Fock states based on loss levels to optimize phase measurement sensitivity in quantum metrology.

Findings

Large photon number difference states perform better at low loss.

States with smaller photon number difference are more robust at high loss.

Sub-shot-noise sensitivity is achievable with certain twin Fock states in lossy environments.

Abstract

To acquire the best path-entangled photon Fock states for robust quantum optical metrology with parity detection, we calculate phase information from a lossy interferometer by using twin entangled Fock states. We show that (a) when loss is less than 50% twin entangled Fock states with large photon number difference give higher visibility while when loss is higher than 50% the ones with less photon number difference give higher visibility; (b) twin entangled Fock states with large photon number difference give sub-shot-noise limit sensitivity for phase detection in a lossy environment. This result provides a reference on what particular path-entangled Fock states are useful for real world metrology applications.