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Critical Investigation of Decoherecne Theory in Different Physical Contexts

Tirandaz, Arash | 2014

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 46565 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry Science
  6. Advisor(s): Shafiee, Afshin
  7. Abstract:
  8. Considering the consistency between the predictions of a theory with what is observed in experience, Quantum Mechanics is the most accurate theory in the history of physics. However, is does not present us an unmbigiuos and realistic description about the nature of the microscopic phenomena. At the heart of these issues is the so-called measurement problem. The formalism of the quantum mechanics is unitary and deterministic. Nevertheles, when one does measurements, the unitary process of the evolution of wave-function breaks due to a stochastic abruption. The results of the measurements are in correspondence with the everyday experience of the observer. Yet, the theory itself does not provide a description for the transition from the quantum to classical realm. One of the alternatives for tackling the problem is the Decoherence theory. Essential differentiation in Decoherence is to discard the closedness requirements of microscopic systems from the standard quantum mechanics. It is emphasized at first time by D. Zeh, a physicsict of institute of theoretical physics in Hiedelberg. Accroding to Decoherence, the evolution of the quantum system is non-unitary and irreversible in correspondence with the essence of quantum measurements. This discontinuity of the evolution of the wave-function is known as the collapse of the wave-function which had been added by von Neumann as one of the postulates of quantum mechanics. Decoherence can make a ground for the description of the apearant collapse for open quantum systems. In the present theses, at first we investigate the non-linear dynamics of open systems in description of quantum phenomena. Then we try to examine the ability of decoherence theory in the description of some well-known experiments in quantum mechanics.
    Considering the spin flop experiments, we will show that under some appropriate approximations, it is possible to find some region in which the predictions of decoherence are incompatible with standard quantum mechanics. Moreover, we will show that for an open system in interaction with its environment, a new from of Heisenberg uncertainty relations may be possible different from the traditional relations presented by quantum mechanics. It imples that open systems behaves like semi classical systems in the limits in which the quantum to classical transitions have been occurred. At last, we examine the role of decoherence theory to investigate the emergence of homochirlaity from the quantum substrate. We show that how the interaction of the superposition of left and right handaed states of a molecule with its environment may be resulted classical mixtures. Then, we illustrate that the action of an asymmetric agent in the presence of decoherence may be responsible for the selection of one of the chiral states from the racemic mixture
  9. Keywords:
  10. Measurement Problem ; Open Quantum System ; Decoherence ; Spin-Flop Experiment ; Heisenberg Uncertaity Principle ; Chirality Problem

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