Mass imbalance effect in resonant Bose-Fermi mixtures
Mass imbalance effect in resonant Bose-Fermi mixtures
复制标题
共振玻色-费米混合物中的质量不平衡效应
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
P. Pieri
中科院分区：
文献类型：
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作者：
E. Fratini;P. Pieri
我们考虑一个均匀的玻色-费米混合物，玻色子-费米子相互作用调谐的Fano-Feshbach共振，在存在的质量和密度之间的两个物种的不平衡。本文首先用多体图解法研究了87 Rb- 40 K非平衡混合物在不同密度不平衡值下的有限温度相图。然后，我们分析了量子相变与玻色子凝聚体在零温度以上的临界玻色子-费米子耦合的消失。我们发现一个明显的依赖性的临界耦合的质量比和密度不平衡的弱依赖性。对于一个极小的玻色子密度，我们推导出，在我们的近似下，在小和大质量比的极限临界耦合的渐近表达式。这些表达式也适用于费米混合物中的极化子-分子跃迁。在足够大的密度不平衡的动量分布函数的分析表明，由于复合费米子和未配对费米子的同时存在，玻色子动量分布中的一个有趣的效果。
We consider a homogeneous Bose-Fermi mixture, with the boson-fermion interaction tuned by a Fano-Feshbach resonance, in the presence of mass and density imbalance between the two species. By using many-body diagrammatic methods, we first study the finite-temperature phase diagram for the specific case of the massimbalanced mixture 87 Rb- 40 K for different values of the density imbalance. We then analyze the quantum phase transition associated with the disappearance at zero temperature of the boson condensate above a critical boson-fermion coupling. We find a pronounced dependence of the critical coupling on the mass ratio and a weak dependence on the density imbalance. For a vanishingly small boson density, we derive, within our approximation, the asymptotic expressions for the critical coupling in the limits of small and large mass ratios. These expressions are relevant also for the polaron-molecule transition in a Fermi mixture at small and large mass ratios. The analysis of the momentum distribution functions at sufficiently large density imbalances shows an interesting effect in the bosonic momentum distribution due to the simultaneous presence of composite fermions and unpaired fermions.