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arXiv 1306.2510cond-mat.quant-gascond-mat.stat-mech
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二维玻色气体Berezinskiii-Kosterlitz-无边界跃迁的普适行为

Universal behavior of two-dimensional bosonic gases at Berezinskii-Kosterlitz-Thouless transitions

G. Ceccarelli, J. Nespolo, A. Pelissetto, E. Vicari

摘要:

本文研究了二维格点玻色气体在Berezinskiii-Kosterlitz-BKT(Berezinskiii-Kosterlitz-Bertelless)相变时的普适临界行为,BKT相变将低温超流相和高温正相分开.为此,我们进行量子蒙特卡罗模拟的硬核玻色-哈伯德(BH)模型在零化学势。我们确定的临界温度,通过使用匹配方法,将有限尺寸的数据BH模型与相应的数据计算在经典的XY模型。在这种方法中,被忽略的标度校正作为晶格尺寸L的倒数幂而不是像在更标准的方法中那样作为1/lnL的幂衰减,使得临界温度的估计更加可靠。然后,我们考虑了存在囚禁谐振势的BH模型,并验证了在BKT临界点处陷阱大小依赖性的普遍性。这个问题与准二维囚禁冷原子的实验有关。

英文摘要:

We study the universal critical behavior of two-dimensional (2D) lattice bosonic gases at the Berezinskii-Kosterlitz-Thouless (BKT) transition, which separates the low-temperature superfluid phase from the high-temperature normal phase. For this purpose, we perform quantum Monte Carlo simulations of the hard-core Bose-Hubbard (BH) model at zero chemical potential. We determine the critical temperature by using a matching method that relates finite-size data for the BH model with corresponding data computed in the classical XY model. In this approach, the neglected scaling corrections decay as inverse powers of the lattice size L, and not as powers of 1/lnL, as in more standard approaches, making the estimate of the critical temperature much more reliable. Then, we consider the BH model in the presence of a trapping harmonic potential, and verify the universality of the trap-size dependence at the BKT critical point. This issue is relevant for experiments with quasi-2D trapped cold atoms.

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