Radial and angular rotons in trapped dipolar gases

We study Bose-Einstein condensates with purely dipolar interactions in oblate traps. We find that the condensate always becomes unstable to collapse when the number of particles is sufficiently large. We analyze the instability, and find that it is the trapped-gas analogue of the "roton-maxon&q...

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Bibliographic Details
Published in:Physical review letters 2007-01, Vol.98 (3), p.030406-030406, Article 030406
Main Authors: Ronen, Shai, Bortolotti, Daniele C E, Bohn, John L
Format: Article
Language:English
Subjects:
BOSE-EINSTEIN CONDENSATION
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
EXCITATION
GASES
INSTABILITY
TRAPPING
TRAPS
WAVE FUNCTIONS
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Summary:We study Bose-Einstein condensates with purely dipolar interactions in oblate traps. We find that the condensate always becomes unstable to collapse when the number of particles is sufficiently large. We analyze the instability, and find that it is the trapped-gas analogue of the "roton-maxon" instability previously reported for a gas that is unconfined in 2D. In addition, we find that under certain circumstances the condensate wave function attains a biconcave shape, with its maximum density away from the center of the gas. These biconcave condensates become unstable due to azimuthal excitation--an angular roton.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.98.030406