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Bose-Einstein condensate in a rapidly rotating nonsymmetric trap

beimu1009 添加于 2010-4-1 10:57 | 1555 次阅读 | 0 个评论

作者
Fetter AL
摘要
A rapidly rotating Bose-Einstein condensate in a symmetric two-dimensional harmonic trap can be described with the lowest Landau-level set of single-particle states. The condensate wave function ψ(x,y) is a Gaussian ∝exp(-r²/2), multiplied by an analytic function f(z) of the complex variable z=x+iy. The criterion for a quantum phase transition to a non-superfluid correlated many-body state is usually expressed in terms of the ratio of the number of particles to the number of vortices. Here a similar description applies to a rapidly rotating nonsymmetric two-dimensional trap with arbitrary quadratic anisotropy (ω_x²<ω_y²). The corresponding condensate wave function ψ(x,y) is a complex anisotropic Gaussian with a phase proportional to xy, multiplied by an analytic function f(z), where z=x+iβ_-y is a stretched complex variable and 0⩽β_-⩽1 is a real parameter that depends on the trap anisotropy and the rotation frequency. Both in the mean-field Thomas-Fermi approximation and in the mean-field lowest Landau level approximation with many visible vortices, an anisotropic parabolic density profile minimizes the energy. An elongated condensate grows along the soft trap direction yet ultimately shrinks along the tight trap direction. The criterion for the quantum phase transition to a correlated state is generalized (1) in terms of N/L_z, which suggests that a nonsymmetric trap should make it easier to observe this transition, or (2) in terms of a “fragmented” correlated state, which suggests that a nonsymmetric trap should make it harder to observe this transition. An alternative scenario involves a crossover to a quasi one-dimensional condensate without visible vortices, as suggested by Aftalion et al., Phys. Rev. A 79, 011603(R) (2009).
详细资料
- 文献种类: Journal Article
- 期刊名称: Physical Review A
- 期刊缩写: Phys. Rev. A
- 期卷页: 2010年第81卷第3期
- ISBN: 1050-2947
学科领域自然科学 » 物理学
标签

BEC Rotating
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