Quantum theory of successive projective measurements

Autor:	Lars M. Johansen
Rok vydání:	2007
Předmět:	Physics Quantum Physics Quantum t-design FOS: Physical sciences Atomic and Molecular Physics and Optics POVM Quantum probability Open quantum system Probability amplitude Quantum state Quantum mechanics Quantum process Quantum information Quantum Physics (quant-ph)
Zdroj:	Physical Review A. 76
ISSN:	1094-1622 1050-2947
DOI:	10.1103/physreva.76.012119
Popis:	We show that a quantum state may be represented as the sum of a joint probability and a complex quantum modification term. The joint probability and the modification term can both be observed in successive projective measurements. The complex modification term is a measure of measurement disturbance. A selective phase rotation is needed to obtain the imaginary part. This leads to a complex quasiprobability, the Kirkwood distribution. We show that the Kirkwood distribution contains full information about the state if the two observables are maximal and complementary. The Kirkwood distribution gives a new picture of state reduction. In a nonselective measurement, the modification term vanishes. A selective measurement leads to a quantum state as a nonnegative conditional probability. We demonstrate the special significance of the Schwinger basis. 6 pages
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b0fba7f8cc43809445dde8f6b290d0ae https://doi.org/10.1103/physreva.76.012119 Zobrazit plný text záznamu