DECOHERENCE IN COMPOSITE QUANTUM OPEN SYSTEMS: THE EFFECTIVENESS OF UNSTABLE DEGREES OF FREEDOM

FERNANDO C. LOMBARDO AND PAULA I. VILLAR

INTERNATIONAL JOURNAL OF MODERN PHYSICS B

World Scientific

Lugar: Singapure; Año: 2006 vol. 20 p. 2951 - 2976

0217-9792

The effect induced by an environment on a composite quantum system is studied. Themodel considers the composite system as comprised by a subsystem A coupled to asubsystem B which is also coupled to an external environment. We studied all possiblefour combinations of subsystems A and B made up with a harmonic oscillator and anupside down oscillator. We analyzed the decoherence suffered by subsystem A due to aneffective environment composed by subsystem B and the external reservoir. In all thecases we found that subsystem A decoheres even though it interacts with the environmentonly through its sole coupling to B. However, the effectiveness of the diffusion depends onthe unstable nature of subsystem A and B. Therefore, the role of this degree of freedomin the effective environment is analyzed in detail.