Quantum Monte Carlo study of the Bose-polaron problem in a one-dimensional gas with contact interactions
Quantum Monte Carlo study of the Bose-polaron problem in a one-dimensional gas with contact interactions
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具有接触相互作用的一维气体中玻色极化子问题的量子蒙特卡罗研究
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
S. Giorgini
中科院分区：
文献类型：
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作者：
L. Parisi;S. Giorgini
本文提出了一种基于量子蒙特卡罗方法的具有接触相互作用的一维系统玻色极化子的理论研究。在这个浸入量子浴的单一杂质问题的例子中，介质是从弱相互作用到唐克斯-吉拉多体系的玻色子的利布-利尼格气体，而杂质通过不同的接触势耦合到量子浴，产生排斥和吸引相互作用。考虑了与介质中粒子具有相同质量的流动杂质和具有无限质量的静态杂质的情况。我们使用精确的数值技术，使我们能够计算杂质的基态能量，它的有效质量以及杂质与浴槽之间的接触参数。这些量作为杂质与浴槽之间以及浴槽内相互作用强度的函数来研究。特别地，我们发现当杂质与弱排斥槽强耦合时，有效质量迅速增加到非常大的值。这种重杂质几乎不在介质内移动，从而实现了朗道-佩卡尔极化子的“自定域”状态。此外，我们将我们的结果与对弱相互作用有效的微扰理论的预测以及当介质中的玻色子表现为不可穿透粒子时可用的精确解进行了比较。
We present a theoretical study based upon quantum Monte Carlo methods of the Bose polaron in one-dimensional systems with contact interactions. In this instance of the problem of a single impurity immersed in a quantum bath, the medium is a Lieb-Liniger gas of bosons ranging from the weakly interacting to the Tonks-Girardeau regime, whereas the impurity is coupled to the bath via a different contact potential producing both repulsive and attractive interactions. Both the case of a mobile impurity, having the same mass as the particles in the medium, and of a static impurity with infinite mass are considered. We make use of exact numerical techniques that allow us to calculate the ground-state energy of the impurity, its effective mass as well as the contact parameter between the impurity and the bath. These quantities are investigated as a function of the strength of interactions between the impurity and the bath and within the bath. In particular, we find that the effective mass rapidly increases to very large values when the impurity gets strongly coupled to an otherwise weakly repulsive bath. This heavy impurity hardly moves within the medium, thereby realizing the "self-localization" regime of the Landau-Pekar polaron. Furthermore, we compare our results with predictions of perturbation theory valid for weak interactions and with exact solutions available when the bosons in the medium behave as impenetrable particles.