Experimental Estimation of Entanglement at the Quantum Limit
G. Brida, Ivo Pietro Degiovanni, Angela Florio, Marco Genovese, Paolo Giorda, Alice Meda, Matteo G. A. Paris, Alexander P. Shurupov · Physical Review Letters · 2010
Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise, experimental feasible measure of entanglement. Nevertheless, such measurements are limited both from experimental uncertainties and intrinsic quantum bounds. Here we present an experiment where the amount of entanglement of a family of two-qubit mixed photon states is estimated with the ultimate precision allowed by quantum mechanics.