Effects of an External Field and Dissipation on Decoherence

Decoherence is the suppression of the interference of quantum states. It plays important roles in the study of the quantum-classical transition. It is also the major obstacle in the implementation of various schemes of quantum computers. Decoherence can be affected by many factors. The interactions between quantum systems of interest and dissipative environments cause the extensively studied environment-induced-decoherence. Decoherence can also occur as the result of a temperature effect. A recent experiment investigated the engineering of decoherence, which involves applying an external field to the quantum system. In this thesis, we study the effect of an external field on decoherence in the case of a harmonic oscillator coupled to a heat bath by calculating its contribution to the attenuation coefficient, which is a measure of decoherence in coordinate space and involves directly observable probability distributions. It is found that, while non-random external force does not result in decoherence, a random external force can lead to intrinsic decoherence that does not require a dissipative environment. The attenuation coefficient for a free harmonic oscillator in a dissipative environment is also calculated using the solution of the initial value quantum Langevin equation. One of the key results obtained is that ”decoherence without dissipation” does not occur in the case of a free harmonic oscillator, in contrast to the case of a free particle.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physical Sciences and Mathematics

Grantor

Physics and Astronomy

Year dc:date.available

2006

Author dc:creator

• Zuo, Jian

• quantum Langevin equation
• the Schrodinger's cat state

Statement dc:rights

• withheld
• Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Identifier

etd-06062006-142409
https://repository.lsu.edu/gradschool_dissertations/13

OAI identifier oai:identifier

oai:repository.lsu.edu:gradschool_dissertations-1012