Ph.D. Theses

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Browsing Ph.D. Theses by Subject "Bose-Einstein condensation."

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    Boundary effects on Bose-Einstein condensation in ultra-static space-times
    (Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2016., 2016.) Ertuğrul, Emine.; Akant, Levent.
    In this theses relativistic boson anti-boson system, inside d dimensional box B with volume V and surface area A, which is a sub-manifold of d dimensional manifold M is studied. Mellin-Barnes Transformations and short time asymptotic of heat kernel are used as mathematical tools. Both Neumann and Dirichlet boundary conditions are considered. Analysis are done for the free energy and charge. Charge is expressed as a function of temperature. E ects of boundaries on temperature is calculated perturbatively. Same methods are employed for studying the neutral gas; free energy and number of particles are studied and again the e ect of boundary on temperature is calculated. Apart from these, upper and lower bounds for depletion coe cient of ideal relativistic bose gas in thermodynamic limit is given with the help of Li-Yau and Colbois-Maerten bounds.
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    Nonrelativistic limit of Bose-Einstein condensation in a static spacetime
    (Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2018., 2018.) İşeri, İslam Çağrı.; Akant, Levent.
    Nonrelativistic limit of thermodynamics of noninteracting Bose field in curved background is investigated via a post-Newtonian approach. In large but finite c limit matter becomes nonrelativistic whereas the geometry stays unchanged. Mellin trans form and heat kernel techniques lead to asymptotics of thermodynamic variables that are used to analyze the gravitational effects on Bose Einstein Condensation in static background. For finite volume, particle density-temperature relation is obtained which include gravitational corrections to the classical expression. Boundary effects due to gravitation are also examined and the results are found to be reduced to usual Minkowski space ones in the absence of gravitation in the thermodynamic limit.