Complete quantum measurements break entanglement

A complete measurement of a quantum observable (POVM) is a measurement of the maximally refined version of the POVM. Complete measurements give information on multiplicities of measurement outcomes and can be used as state preparation procedures. Moreover, any observable can be measured completely. In this Letter, we show that a complete measurement breaks entanglement completely between the system, ancilla and their environment. Finally, consequences for the quantum Zeno effect and complete position measurements are discussed.

► Any quantum observable (POVM) can be measured completely.
► A complete measurement is a measurement of the maximally refined POVM.
► A complete measurement breaks entanglement completely.
► Complete measurements can be viewed as state preparation procedures.
► We define the complete quantum Zeno effect and complete position measurements.