We chooseˆUG = ˆUBS ˆRA(ϕ), where ˆRA(ϕ)=e −iϕˆa† ˆais a local rotation operator and ˆUBS(π/4)=exp h π/4 ˆa† ˆb−ˆaˆb† i is a balanced beam-splitter

This yields fG ≥λ 2 max ˆI|ψNOON⟩ = 1 2

1 Pith paper cite this work. Polarity classification is still indexing.

1 Pith paper citing it