Particle vs. Mode Entanglement in Optical Quantum Metrology
Nicolás Quesada, Jaspreet Sahota · 2015
We present a constructive proof of the fact that mode entanglement is not necessary for optical quantum enhanced metrology (QEM) but particle entanglement is. We provide a particle entanglement witness that detects all path symmetric states useful for QEM in a Mach-Zender interferometer.