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Aspects of decoherence in quantum systems.

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Author(s):
Andréa Nemes Salgueiro
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
Defense date:
Examining board members:
Antonio Fernando Ribeiro de Toledo Piza; Antonio Vidiella Barranco; Amir Ordacgi Caldeira; Salomon Sylvain Mizrahi; Paulo Alberto Nussenzveig
Advisor: Antonio Fernando Ribeiro de Toledo Piza
Abstract

We study the quantum decoherence process in different contexts. In particular, we study decoherence effects in the dynamics of a two-level system coupled to another system which has a continuous energy spectrum. We also investigate when the master equation description, in a Born Markov approximation reproduces the exact solution. We extend this investigation to the model which describes the interaction between a harmonic oscillator and a thermal bath of harmonic oscillators in the rotating wave approximation. We also study the two atom correlation scheme originally proposed by Davidovich, Brune, Raimond and Haroche for measuring the decoherence of a mesoscopic superposition of coherent states of a QED cavity in the context of quantum computation. We show that this experiment is equivalent to a quantum computer solving Deutsch\'s problem. We find a way to reduce the errors due to decoherence. Finally, we show how the Zeno effect is related to the decoherence process. (AU)