Can we make sense out of the measurement process in relativistic quantum mechanics

Journal Article · Wed Jul 15 00:00:00 EDT 1981 · Phys. Rev. D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.24.359· OSTI ID:6310655

Aharonov, Y; Albert, D Z

We study the instantaneity of the state-reduction process in relativistic quantum mechanics. The conclusion of various authors that this instantaneity will restrict the set of relativistic observables to purely local ones (i.e., that the measurement of any nonlocal property of a system at a well-defined time would give rise to violations of relativistic causality) is found to be erroneous, and experiments (of a kind not encountered before in measurement theory) are described whereby certain nonlocal properties of some simple physical systems can be measured at a well-defined time without violating causality. The attempts of certain authors to reconcile the reduction process with the covariance of the relativistic quantum state are considered and found wanting, and it is argued that the covariance of relativistic quantum theories resides exclusively in the experimental probabilities, and not in the underlying quantum states. The problem of nonlocal measurement is considered in general: distinctions (which are not to be met with in the nonrelativistic case) arise in relativistic quantum mechanics between what can be measured for fermions and what can be measured for bosons, between what can be measured for individual systems and what can be measured for ensembles, and between what kinds of states can be verified by measurement and what kinds of states can be prepared by measurement; and these pose difficult questions about the nature of measurement itself.

• Research Organization: Physics Department, Tel Aviv University, Ramat Aviv, Israel
• DOE Contract Number: DE-AC02-76ER02232B.000
• OSTI ID: 6310655
• Journal Information: Phys. Rev. D; (United States), Vol. 24:2
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
QUANTUM MECHANICS
MEASURE THEORY
EIGENFUNCTIONS
LORENTZ TRANSFORMATIONS
PROBABILITY
RELATIVITY THEORY
SPACE-TIME
WAVE FUNCTIONS
FIELD THEORIES
FUNCTIONS
GENERAL RELATIVITY THEORY
MATHEMATICS
MECHANICS
TRANSFORMATIONS
657002* - Theoretical & Mathematical Physics- Classical & Quantum Mechanics