Format:
1 Online-Ressource (154 Seiten, 13714 KB)
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Diagramme, Illustrationen
Content:
The subject of the present thesis is the one-dimensional Bose gas. Since long-rang order is destroyed by infra-red fluctuations in one dimension, only the formation of a quasi-condensate is possible, which exhibits suppressed density fluctuations, but whose phase fluctuates strongly. It is shown that modified mean-field theories based on a symmetry-breaking approach can even characterise phase coherence properties of such a quasi-condensate properly. A correct description of the transition from the degenerate ideal Bose gas to the quasi-condensate, which is a smooth cross-over rather than a phase transition, is not possible though. Basic conditions for the applicability of the theories are not fulfilled in this regime, such that the existence of a critical point is predicted. The theories are compared on the basis of their excitation sprectum, equation of state, density fluctuations and related correlation functions. High-temperature expansions of the corresponding integrals are derived analytically for the numerical evaluation ...
Note:
Masterarbeit Universität Potsdam 2015
Language:
English
Keywords:
Hochschulschrift
URN:
urn:nbn:de:kobv:517-opus4-87247
URL:
https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-87247
URL:
https://d-nb.info/1218601892/34
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