Quantum-enhanced phase estimation with an amplified Bell state
Jaspreet Sahota, Daniel F. V. James · Physical Review A · 2013
We propose a phase estimation protocol for optical interferometry that employs a probe state (containing on average $\overline{n}$ photons) obtained by squeezing each mode, separately, of a single photon path entangled Bell state. This scheme involves a Mach-Zehnder type interferometer for which each mode is squeezed after the first beam splitter. Information about the differential phase is extracted using a parity detection and the resulting measurement signal is super-resolving and supersensitive, with a minimum phase uncertainty $\ensuremath{\Delta}\ensuremath{\varphi}=2/(\overline{n}+1)$. This probe state can be generated with current technologies where $\overline{n}$ is in the order of many thousands of photons.