Anomalous values, Fisher information, and contextuality, in generalized quantum measurements. (17th March 2020)

• Record Type: Journal Article
• Authors: Cimini, Valeria; Gianani, Ilaria; Piacentini, Fabrizio; Degiovanni, Ivo Pietro; Barbieri, Marco
• Is Part Of: Quantum science and technology. Volume 5:Number 2(2020)
• Publication Date: 2020-03-17
• Subjects: quantum measurements -- weak values -- contextually -- quantum metrology; Quantum theory -- Periodicals; Quantum theory; Periodicals; 530
• DOI: 10.1088/2058-9565/ab7988
• Languages: English
• ISSNs: 2058-9565

Abstract

Abstract: Postselection following weak measurements has long been investigated for its peculiar manifestation of quantum signatures. In particular, the postselected events can give rise to anomalous values lying outside the spectrum of the measured quantity, and may provide enhanced Fisher information. Furthermore, the Pusey inequality highlights that, for extremely weak measurements, non-contextual models cannot account for the outcome probabilities. It is then interesting to investigate whether these are linked in a unified framework. Here we discuss on the existence of a possible connection in the case of qubits. We show that when performing generic postselected measurements there exist no one-to-one mapping between them, an instance that leads to drawing more involved considerations.