arXiv 0912.31962009-12cond-mat.quant-gascond-mat.str-el

三体约束格点玻色气体的量子场论--II：在多体问题中的应用

Quantum Field Theory for the Three-Body Constrained Lattice Bose Gas -- Part II: Application to the Many-Body Problem

S. Diehl, M. Baranov, A. J. Daley, P. Zoller

备注：: 22 pages, 5 figures
发表信息：: Phys. Rev. B 82, 064510 (2010)
DOI：: 10.1103/PhysRevB.82.064510

摘要：

我们分析了吸引格点玻色子的基态相图，这些玻色子是由一个三体现场硬核约束稳定的。这个模型的一个显著特点是从一个常规的原子超流体的伊辛型过渡到一个二聚体超流体与消失的原子凝聚。该研究建立在约束模型到具有多项式相互作用的耦合玻色子理论的精确映射上，该理论在相关论文中提出[11]。在这个框架中，我们专注于分析手段的相图方面，这些方面与相互作用密切相关，因此在平均场加自旋波方法中无法访问。首先，我们确定的平均场相边界，这是最明显的低密度制度的转变。其次，强耦合极限的调查揭示了一个新的集体模式的存在，这是由于在这个政权的对称性增强。第三，我们表明，伊辛型相变，驱动一阶通过竞争的长波长模式在通用的填充，终止到一个真正的伊辛量子临界点附近的半填充。

英文摘要：

We analyze the ground state phase diagram of attractive lattice bosons, which are stabilized by a three-body onsite hardcore constraint. A salient feature of this model is an Ising type transition from a conventional atomic superfluid to a dimer superfluid with vanishing atomic condensate. The study builds on an exact mapping of the constrained model to a theory of coupled bosons with polynomial interactions, proposed in a related paper [11]. In this framework, we focus by analytical means on aspects of the phase diagram which are intimately connected to interactions, and are thus not accessible in a mean field plus spin wave approach. First, we determine shifts in the mean field phase border, which are most pronounced in the low density regime. Second, the investigation of the strong coupling limit reveals the existence of a new collective mode, which emerges as a consequence of enhanced symmetries in this regime. Third, we show that the Ising type phase transition, driven first order via the competition of long wavelength modes at generic fillings, terminates into a true Ising quantum critical point in the vicinity of half filling.

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