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| Identifier |
000381544 |
| Title |
Artificial magnetic fields in Bose Einstein condensates |
| Alternative Title |
Τεχνητά μαγνητικά πεδία στα συμπυκνώματα Bose-Einstein |
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Author
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Ρούσσου, Αλεξάνδρα Δ.
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Thesis advisor
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Παπανικολάου, Νικόλαος
Κομηνέας, Σταύρος
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| Abstract |
We study an atomic gas of bosons where the atoms come from vapours of alkali metal atoms. This Bose gas is very dilute and therefore the interactions between atoms are really weak. In experiments the atoms are confined by a trapping potential which is usually a harmonic one. A series of cooling techniques are used to cool the system to very low temperatures, where the atoms occupy the lowest energy state and a Bose-Einstein condensate is formed. The BEC is expected to behave as a super fluid. Quantized vortices are expected to form as a result of rotation of the BEC. The number of vortices increase with the rotation frequency and a vortex lattice is formed when the frequency approaches the frequency of the trapping potential. In the case of very small interactions the problem is analogous to the planar motion of charged particles under a perpendicular magnetic field. One can define an effective magnetic field Beff which is analogous to the rotation frequency. The energy levels of the charged particles are the Landau Levels. In the weak interaction limit the Lowest Landau Level is enough to describe the behaviour of the BEC and the formation of vortices. A succession of vortex states is obtained in the BEC : vortices enter in the condensate as the rotation frequency is increased. Accordingly the angular momentum l of this quantum system increases. For angular momentum values 0 ≤ l ≤ 1 minimisation of the energy of the rotating system is obtained by an analytic wavefunction given in Ref. [3]. This wavefunction indicates that a single vortex enters in the condensate from spatial infinity at a critical rotation frequency. The vortex can move continuously to the center of the condensate where the angular momentum of the condensate is l = 1.
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| Language |
English |
| Subject |
Low temperatures |
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Lower Landau level |
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Superfluid |
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Vortices |
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Δίνες |
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Υπέρρευστο |
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Χαμηλές θερμοκρασίες |
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Χαμηλότερο ενεργειακό επίπεδο Landau |
| Issue date |
2013-11-15 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
648 |
Artificial magnetic fields in Bose Einstein condensates
