Adaptive strategy for joint measurements

Understand

We develop a technique to find simultaneous measurements for noisy quantum observables in finite-dimensional Hilbert spaces.

• We use the method to derive lower bounds for the noise needed to make incompatible measurements jointly measurable.
• Using our strategy together with recent devel- opments in the field of one-sided quantum information processing we show that the attained lower bounds are tight for various symmetric sets of quantum measurements.
• We use this characterisation to prove the existence of so called 4-Specker sets in the qubit case.