Will M, Astrakharchik G E, Fleischhauer M
Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany.
Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034, Barcelona, Spain.
Phys Rev Lett. 2021 Sep 3;127(10):103401. doi: 10.1103/PhysRevLett.127.103401.
Bose polarons, quasiparticles composed of mobile impurities surrounded by cold Bose gas, can experience strong interactions mediated by the many-body environment and form bipolaron bound states. Here we present a detailed study of heavy polarons in a one-dimensional Bose gas by formulating a nonperturbative theory and complementing it with exact numerical simulations. We develop an analytic approach for weak boson-boson interactions and arbitrarily strong impurity-boson couplings. Our approach is based on a mean-field theory that accounts for deformations of the superfluid by the impurities and in this way minimizes quantum fluctuations. The mean-field equations are solved exactly in the Born-Oppenheimer approximation, leading to an analytic expression for the interaction potential of heavy polarons, which is found to be in excellent agreement with quantum Monte Carlo (QMC) results. In the strong coupling limit, the potential substantially deviates from the exponential form valid for weak coupling and has a linear shape at short distances. Taking into account the leading-order Born-Huang corrections, we calculate bipolaron binding energies for impurity-boson mass ratios as low as 3 and find excellent agreement with QMC results.
玻色极化子是由被冷玻色气体包围的移动杂质组成的准粒子，它可以经历由多体环境介导的强相互作用并形成双极化子束缚态。在此，我们通过构建一种非微扰理论并辅以精确的数值模拟，对一维玻色气体中的重极化子进行了详细研究。我们针对弱玻色子 - 玻色子相互作用和任意强的杂质 - 玻色子耦合发展了一种解析方法。我们的方法基于一种平均场理论，该理论考虑了杂质对超流体的形变，从而以这种方式最小化量子涨落。平均场方程在玻恩 - 奥本海默近似下被精确求解，得到了重极化子相互作用势的解析表达式，发现它与量子蒙特卡罗（QMC）结果高度吻合。在强耦合极限下，该势与弱耦合时有效的指数形式有很大偏差，在短距离处呈线性形状。考虑到领先阶的玻恩 - 黄修正，我们计算了杂质 - 玻色子质量比低至3时的双极化子结合能，发现与QMC结果高度吻合。
