Entropy and uncertainty of squeezed quantum open systems

Don Koks, Andrew Matacz, and B. L. Hu
Phys. Rev. D 55, 5917 – Published 15 May 1997; Erratum Phys. Rev. D 56, 5281 (1997)
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Abstract

We define the entropy S and uncertainty function of a squeezed system interacting with a thermal bath, and study how they change in time by following the evolution of the reduced density matrix in the influence functional formalism. As examples, we calculate the entropy of two exactly solvable squeezed systems: an inverted harmonic oscillator and a scalar field mode evolving in an inflationary universe. For the inverted oscillator with weak coupling to a bath at both high and low temperatures, Sr, where r is the squeeze parameter. In the de Sitter case, at high temperatures, S(1c)r where c=γ0/H, γ0 being the coupling to the bath and H the Hubble constant. These three cases confirm previous results based on more ad hoc prescriptions for calculating entropy. But at low temperatures, the de Sitter entropy S(1/2c)r is noticeably different. This result, obtained from a more rigorous approach, shows that factors usually ignored by the conventional approaches, i.e., the nature of the environment and the coupling strength betwen the system and the environment, are important.

  • Received 2 December 1996

DOI:https://doi.org/10.1103/PhysRevD.55.5917

©1997 American Physical Society

Erratum

Erratum: Entropy and uncertainty of squeezed quantum open systems [Phys. Rev. D 55, 5917 (1997)]

Don Koks, Andrew Matacz, and B. L. Hu
Phys. Rev. D 56, 5281 (1997)

Authors & Affiliations

Don Koks

  • Department of Physics, University of Adelaide, Adelaide SA 5005, Australia

Andrew Matacz

  • School of Mathematics and Statistics, University of Sydney, Sydney NSW 2006, Australia

B. L. Hu

  • Department of Physics, University of Maryland, College Park, Maryland 20742

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Issue

Vol. 55, Iss. 10 — 15 May 1997

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