Bose Einstein Condensation
Mostrando 13-24 de 36 artigos, teses e dissertações.
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13. Teorias variacionais dos sistemas formados por atomos de 4He / Variational theories for systems of 4He atoms
This work proposes two variational wave functions based on the concept of shadow particles that describes the solid phase of systems formed by atoms of 4He. One of them, called Periodic Free Shadow Wave Function (PFS) provides good results for this phase like the energies of the system and the Radial Distribution Function that proved to be in good agreement
Publicado em: 2008
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14. Perturbações temporais em condensados de Bose-Einstein diluídos e vórtice em condensados densos / Time dependent perturbation in dilude Bose Einstein Condensate and vortex in dense condensate.
In this work we studied the soliton interactions between two solitons under time dependent perturbations in a trap potential and interparticule potential. In a dense Bose-Einstein condensate we studied the insertion of kinetic term going beyond the Thomas-Fermi approximation and its effect in critical frequency of vortices formation.
Publicado em: 2007
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15. Two-dimensional critical Potts and its tricritical shadow
These notes give examples of how suitably defined geometrical objects encode in their fractal structure thermal critical behavior. The emphasis is on the two-dimensional Potts model for which two types of spin clusters can be defined. Whereas the Fortuin-Kasteleyn clusters describe the standard critical behavior, the geometrical clusters describe the tricrit
Brazilian Journal of Physics. Publicado em: 2006-09
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16. Teoria de detecção homodina atomica em condensados de Bose-Einstein / Atomic homodyne detection theory on Bose-Einstein condensates
Óptica atômica e em particular a física de ondas de matéria ultrafrias tiveram um grande desenvolvimento teórico e experimental em muito devido à realização experimental da condensação de Bose-Einstein em vapores atômicos. A gama de interesse nesses sistemas é muito ampla já que eles proporcionam reais aplicações práticas de assuntos inovador
Publicado em: 2006
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17. Monitoramento de propriedades de condensados de Bose-Einstein interagindo não ressonantemente com campos óticos via detecção contínua de fotóns
In this work we consider an of - resonant interaction between optical fields and a Bose - Einstein condensation. We used a continuous photo detection model to study the efects of the counting of k photons of the optical field upon the properties of the atoms in the condensate. We have obtained the density operator of the interacting system conditioned to cou
Publicado em: 2006
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18. Thermodynamics of an ideal gas of bosons harmonically trapped: equation of state and susceptibilities
We present theoretical aspects concerning the thermodynamics of an ideal bosonic gas trapped by a harmonic potential. Working in the Grand Canonical ensemble we are able to properly identify the extensive thermodynamic variable equivalent to the volume and the intensive thermodynamic variable equivalent to the pressure. These are called the "harmonic volume"
Brazilian Journal of Physics. Publicado em: 2005-09
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19. Quantum atom optics with trapped Bose-Einstein condensates
Both Bose-Einstein condensates and optical fields are composed of bosons, so that the majority of the processes which have long been studied in quantum and nonlinear optics have equivalents in the field of Bose-Einsten condensation. However, due to the masses of the condensed atoms, the confining potentials and the huge collisional nonlinearities, the simple
Brazilian Journal of Physics. Publicado em: 2004-12
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20. Bose-Einstein condensation in dilute atomic gases
The material presented here consists of lecture notes written for a five two-hour sections course given during the 2004 edition of the Brazilian School on Statistical Mechanics. The topics covered are 1. Bose-Einstein condensation of trapped ideal gases; 2. Effective two-body interactions and exact results in the Gross-Pitaevski limit; 3. Atomic structure ef
Brazilian Journal of Physics. Publicado em: 2004-09
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21. Considerations on undistorted-progressive X-waves and Davydov solitons, Fröhlich-Bose-Einstein condensation, and Cherenkov-like effect in biosystems
Research in ultrasonography has evidenced the propagation of a peculiar kind of excitation in fluids. Such excitation, dubbed a X-wave, has characteristics resembling that of a solitary-wave type. We reconsider the problem in a medium consisting of a biological material of the like of alpha-helix proteins. It can be shown that in this case is expected an exc
Brazilian Journal of Physics. Publicado em: 2004-06
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22. Systems Biology: an information-theoretic-based thermo-statistical approach
Systems Biology (system-level understanding in biological science), from the physical-chemical point of view, is involved with irreversible thermodynamics and nonlinear kinetic theory of open systems which are founded on nonequilibrium statistical mechanics. We describe a modern thermo-statistical approach for dealing with complex systems, in particular biol
Brazilian Journal of Physics. Publicado em: 2004-06
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23. Efeitos de Densidade nos Processos de Fotoassociação em Condensados de Bose-Einstein
Nesta tese abordaremos os processos de fotoassociação em condensação de Bose- Einstein. Estes podem ser resumidos da seguinte forma: um condensado formados por átomos, inicialmente no estado fundamental, é iluminado com laseres de freqüência adequada, de tal modo que os átomos se combinem em moléculas. Tudo isto sem que o condensado deixe de existi
Publicado em: 2004
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24. Obtenção da degenerescência quântica em sódio aprisionado / Achievement of quantum degeneracy in trapped sodium
Usando a técnica de resfriamento evaporativo para átomos comprimidos numa armadilha magnética tipo QUIC, implementamos experimentos para observar Condensação de Bose-Einstein de átomos de sódio. Nessa armadilha magnética temos átomos advindos de uma armadilha magneto-óptica, a qual é carregada por um feixe desacelerado como etapa de pré-resfriame
Publicado em: 2004