Entropy balance in pure interactions of open quantum systems

Journal Article · Wed Feb 01 00:00:00 EST 1989 · International Journal of Theoretical Physics; (USA)

DOI:https://doi.org/10.1007/BF00669806· OSTI ID:5504486

Urigu, R ^[1]

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1. Politecnico di Torino (Italy)

Processes are considered in which a statistical ensemble w of quantum systems is split into ensembles, or channels (w{sub i}), conditional to the occurrence, with respective probabilities (p{sub i}{w}), of associated macroscopic effects. These processes are described here by a family of operations T{sub i}: w {yields} p{sub i}{sup w} w{sub i}{sub T}, which remarkably generalize the usual state reductions of the nondestructive measurements. In a previous work it was proved that the microscopic entropy of the given open system decreases or at most remains constant if all the T{sub i} are pure operations, i.e., they transform pure states into pure states; it is proved here that the increase in entropy of the external world, computed as S{sup Tm}(w) = {minus} {Sigma}{sub i}p{sub i}{sup w}lg p{sub i}{sup w}, is sufficient to compensate for such an entropy decrease whenever the T{sub i} are all pure operations of the first kind, whereas whenever some T{sub i} is pure of the second kind (or nonpure, too), the total entropy, computed as above, may decrease.

• OSTI ID: 5504486
• Journal Information: International Journal of Theoretical Physics; (USA), Vol. 28:2; ISSN 0020-7748
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
INTERACTIONS
ENTROPY
QUANTUM MECHANICS
ENERGY BALANCE
HILBERT SPACE
IRREVERSIBLE PROCESSES
MATHEMATICAL MODELS
MATRICES
MEASURE THEORY
PROBABILITY
QUANTUM OPERATORS
SCATTERING
STATISTICAL MECHANICS
THERMODYNAMICS
BANACH SPACE
MATHEMATICAL OPERATORS
MATHEMATICAL SPACE
MATHEMATICS
MECHANICS
PHYSICAL PROPERTIES
SPACE
THERMODYNAMIC PROPERTIES
657002* - Theoretical & Mathematical Physics- Classical & Quantum Mechanics