Using Entanglement Improves the Precision of Quantum Measurements
Giacomo Mauro D’Ariano, Paoloplacido Lo Presti, Matteo G. A. Paris · Physical Review Letters · 2001
We show how entanglement can be used to improve the estimation of an unknown transformation. Using entanglement is always of benefit in improving either the precision or the stability of the measurement. Examples relevant for applications are illustrated, for either qubits or continuous variables.