Universality of sequential quantum measurements
: Teiko Heinosaari, Takayuki Miyadera
Publisher: AMER PHYSICAL SOC
: 2015
: Physical Review A
: PHYSICAL REVIEW A
: PHYS REV A
: 022110
: 91
: 2
: 6
: 1050-2947
DOI: https://doi.org/10.1103/PhysRevA.91.022110
We show that any jointly measurable pair of quantum observables can be obtained in a sequential measurement scheme, even if the second observable will be decided after the first measurement. This means that it is possible to perform a measurement of any quantum observable in a way that does not disturb the subsequent measurements more than is dictated by joint measurability. Only measurements with a specific structure have this universality feature. As a supplementing result, we provide a characterization of all possible joint measurements obtained from a sequential measurement lacking universality.