Exploring the ultimate limits: super-resolution enhanced by partial coherence

The resolution of separation two elementary signals forming a partially coherent superposition, defined by quantum Fisher information and normalized with respect to detection probabilities, is always limited the incoherent mixtures. However, when superpositions are prepared in controlled way, precision can be enhanced up several orders magnitude above this limit. Coherence also allows sorting about various parameters into distinct channels as demonstrated parameter linked anti-phase superposition centroid position in-phase superposition.