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arXiv · 2101.11997

Polaron Interactions and Bipolarons in One-Dimensional Bose Gases in the Strong Coupling Regime

Martin Will·Gregory E. Astrakharchik·Michael Fleischhauer
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Abstract

Bose polarons, quasi-particles 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 non-perturbative 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 Born-Oppenheimer (BO) 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.

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Martin Will, Gregory E. Astrakharchik, Michael Fleischhauer. 2021-01-28. Polaron Interactions and Bipolarons in One-Dimensional Bose Gases in the Strong Coupling Regime. https://doi.org/10.1103/physrevlett.127.103401

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