TY - JOUR
T1 - Purity Estimation with Separable Measurements
JF - Physical Review Letters
Y1 - 2005
A1 - Bagan, Emili
A1 - Ballester, M. A.
A1 - Muñoz-Tapia, Ramon
A1 - Romero-Isart, Oriol
AB - Given a large number N of copies of a qubit state of which we wish to estimate its purity, we prove that separable-measurement protocols can be as efficient as the optimal joint-measurement one if classical communication is used. This shows that the optimal estimation of the entanglement of a two-qubit state can also be achieved asymptotically with fully separable measurements. Thus, quantum memories provide no advantage in this situation. The relationship between our global Bayesian approach and the quantum Cramér-Rao bound is discussed.
PB - American Physical Society
VL - 95
UR - http://link.aps.org/doi/10.1103/PhysRevLett.95.110504
ER -