We address the use of entanglement to improve the precision of generalized quantum interferometry, i.e. of binary measurements aimed to determine whether or not a perturbation has been applied by a given device. For the most relevant operations in quantum optics, we evaluate the optimal detection strategy and the ultimate bounds to the minimum detectable perturbation. Our results indicate that entanglement-assisted strategies improve the discrimination in comparison with conventional schemes. A concrete setup to approach performances of the optimal strategies is also suggested.
@article{arxiv.quant-ph/0110105,
title = {Improving quantum interferometry by using entanglement (to take a decision you'd better use entanglement)},
author = {G. M. D'Ariano and Matteo G. A Paris and Paolo Perinotti},
journal= {arXiv preprint arXiv:quant-ph/0110105},
year = {2007}
}