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Binding Energy of Multi-Partite Quantum Systems based on Quantum Thermodynamics Viewpoint

Afsary, Maryam | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53484 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Bahrampour, Alireza; Rezakhani, Ali
  7. Abstract:
  8. Examining composite quantum systems through quantum thermodynamics, we face the new concept of binding energy. In this thesis, we are going to present a general definition for binding energy in quantum systems which covers any kind of interactions. First of all, we examine the possibility of energy exchange in a quantum system using quantum thermodynamics. In this theory, energy exchanges of an open quantum system may be divided in to two portions: heat and work; due to an accepted definition, heat is the portion of energy that is supposed to change entropy, while work has no influence on that. In this research, we restrict our calculations to the systems which are thermally closed and experience unitary evolutions. After a brief introduction to the control theory, an external field is applied in a controlled manner to remove the interaction between the subsystems. In such a process, the binding energy is defined as the optimum energy difference between the initial and final states in such a way that the subsystems has no influence on each other at the end of the process. Employing quantum optimal control theory, the bond breaking occurs at minimum time with minimum energy. A direct result of optimization is elimination of correlations and passivation of final state that means no energy can be extracted from the separated systems in cyclic evolutions. The optimum bond breaking is applied using a sequence of laser pulses for each of which we can calculate the intensity and the phase. To reduce the energy needed during the bond breaking process, we also employ another controlling method: quantum tunneling. This phenomenon makes the bond breaking process probabilistic and the final time of the process undetermined, thus we need to update the binding energy definition to cover such processes
  9. Keywords:
  10. Open Quantum System ; Tunneling ; Thermodynamics ; Optimal Control ; Binding Energy ; Correlation ; Heat ; Work Coefficient

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