Bipolarons and multipolarons consisting of impurity atoms in a Bose-Einstein condensate

被引:43
作者
Casteels, W. [1 ]
Tempere, J. [1 ,2 ]
Devreese, J. T. [1 ]
机构
[1] Univ Antwerp, TQC, B-2610 Antwerp, Belgium
[2] Harvard Univ, Lyman Lab Phys, Cambridge, MA 02138 USA
来源
PHYSICAL REVIEW A | 2013年 / 88卷 / 01期
关键词
MIXTURES; POLARONS; STATES;
D O I
10.1103/PhysRevA.88.013613
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
The variational Feynman formalism for the polaron, extended to an all-coupling treatment of bipolarons, is applied for two impurity atoms in a Bose-Einstein condensate. This shows that if the polaronic coupling strength is large enough, the impurities will form a bound state (the bipolaron). As a function of the mutual repulsion between the impurities, two types of bipolaron are distinguished: a tightly bound bipolaron at weak repulsion and a dumbbell bipolaron at strong repulsion. Apart from the binding energy, the evolution of the bipolaron radius and its effective mass are also examined as a function of the strength of the repulsive interaction between the impurities and of the polaronic coupling strength. We then apply the strong-coupling formalism to multiple-impurity atoms in a condensate, which leads to the prediction of multipolaron formation in the strong-coupling regime. The results of the two formalisms are compared for two impurities in a condensate, which results in a general qualitative agreement and a quantitative agreement at strong coupling. Typically, the system of impurity atoms in a Bose-Einstein condensate is expected to exhibit the polaronic weak-coupling regime. However, the polaronic coupling strength is, in principle, tunable with a Feshbach resonance.
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页数:12
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