Two questions on quantum probability
: Lahti P, Pellonpaa JP, Ylinen K
Publisher: ELSEVIER SCIENCE BV
: 2005
Physics Letters A
PHYSICS LETTERS A
: PHYS LETT A
: 339
: 1-2
: 18
: 22
: 5
: 0375-9601
DOI: https://doi.org/10.1016/j.physleta.2005.03.041
Determining a quantum observable from the first and second moments of its measurement outcome statistics is investigated. Operational conditions for the moments of a probability measure are given which suffice to determine the probability measure. Differential operators are shown to lead to physically relevant cases where the expectation values of large classes of noncommuting observables do not distinguish superpositions of states and, in particular, where the full moment information does not determine the probability measure. (c) 2005 Elsevier B.V. All rights reserved.