Year: 2015
Type: dissertation
Abstract: The subject of the present thesis is the study of the interaction between a Bose-Einstein condensate (BEC) and a superconductor.The BEC performs center-of-mass oscillations perpendicular to the superconducting surface.Each atom in the BEC carries a magnetic dipole moment, which induces eddy currents in the surface.These eddy currents are a source of a magnetic field which modifies the potential in which the BEC is trapped.This leads to a change of the dynamical behavior of the BEC.In particular the BEC center-of-mass oscillation frequency is shifted compared to the case without the surface interaction.Additionally, the potential generated by the superconductor excites shape oscillations of the BEC.To investigate these effects, the Gross-Pitaevskii equation for a dipolar BEC close to a superconducting surface is solved numerically.Also analytical approximations are presented and compared to the numerically obtained results.It is shown that the interaction with the superconducting surface generates a frequency shift, that is large enough to be detected in an experiment.Furthermore, different methods to identify the eddy current effect are presented.It is also discussed how the effects on the BEC can be enhanced by choosing the proper dipole orientation and by adjusting the geometry of the setup.The BEC shape oscillations can be additionally enhanced by making use of a resonance phenomenon.4 Center-of-mass frequency shift 4.1 Frequency shift within TF approximation . . . . . . . . . .4.1.1Frequency shift based on a Thomas-Fermi ellipsoid 4.1.2Frequency shift based on the column density model 4.2 Numerical results for the frequency shift . . . . . . . . . . .4.3 Different polarizations of the BEC . . . . . . . . . . . . . .4.3.1 Polarization in the y-direction . . . . . . . . . . . .4.3.2Polarization in the x-direction (perpendicular to the surface) . . . . . . . . . . .
Author: Igor Sapina
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W765706284