Bose polarons in ultracold atoms in one dimension: beyond the Frohlich paradigm
Bose polarons in ultracold atoms in one dimension: beyond the Frohlich paradigm
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DOI：
10.1088/1367-2630/aa8a2e
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发表时间：
2017-10-25
影响因子：
3.3
通讯作者：
Demler, Eugene
中科院分区：
文献类型：
--
作者：
Grusdt, Fabian;Astrakharchik, Gregory E.;Demler, Eugene
沉浸在玻色-爱因斯坦凝聚体中的移动的杂质原子为研究玻色极化子提供了一个新的平台。最近在超冷原子领域的实验进展使得有可能实现这样的系统具有高度可调的微观参数和探索极化子的平衡和动力学性质，使用丰富的原子物理工具箱。本文对一维超冷原子系统中的玻色极化子进行了详细的理论分析。通过结合非微扰重整化群方法与数值精确的扩散蒙特卡罗计算，我们不仅得到了详细的数值结果在很宽的参数范围内，但也定性的了解系统的不同制度。我们发现，一个准确的描述玻色极化子需要列入两个声子散射条款，这超出了常用的Frohlich模型。此外，我们表明，当玻色气体是在强相互作用的制度，需要包括声子模式之间的相互作用。我们用几种理论方法计算了极化子的能量和有效质量。前者可以用射频光谱测量，后者可以用谐波捕获势中的杂质振荡进行实验研究。我们将我们的有效质量理论结果与Catani等人的实验（2012 Phys. Rev. A85 023623）进行了比较。在弱到中等耦合制度，我们得到了很好的定量之间的理论和实验的协议，没有任何自由拟合参数。我们补充我们的分析，全动力学模拟极化子振荡在浅囚禁势。我们还使用我们的重整化群方法来分析完整的相图，并确定区域，支持排斥和吸引极化子，以及多粒子束缚态。
Mobile impurity atoms immersed in Bose-Einstein condensates provide a new platform for exploring Bose polarons. Recent experimental advances in the field of ultracold atoms make it possible to realize such systems with highly tunable microscopic parameters and to explore equilibrium and dynamical properties of polarons using a rich toolbox of atomic physics. In this paper we present a detailed theoretical analysis of Bose polarons in one-dimensional systems of ultracold atoms. By combining a non-perturbative renormalization group approach with numerically exact diffusion Monte Carlo calculations we obtain not only detailed numerical results over a broad range of parameters but also qualitative understanding of different regimes of the system. We find that an accurate description of Bose polarons requires the inclusion of two-phonon scattering terms which go beyond the commonly used Frohlich model. Furthermore we show that when the Bose gas is in the strongly interacting regime, one needs to include interactions between the phonon modes. We use several theoretical approaches to calculate the polaron energy and its effective mass. The former can be measured using radio-frequency spectroscopy and the latter can be studied experimentally using impurity oscillations in a harmonic trapping potential. We compare our theoretical results for the effective mass to the experiments by Catani et al (2012 Phys. Rev. A85 023623). In the weak-to-intermediate coupling regimes we obtain excellent quantitative agreement between theory and experiment, without any free fitting parameter. We supplement our analysis by full dynamical simulations of polaron oscillations in a shallow trapping potential. We also use our renormalization group approach to analyze the full phase diagram and identify regions that support repulsive and attractive polarons, as well as multi-particle bound states.