Exact results for polaron and molecule in one-dimensional spin-1/2 Fermi gas

Runxin Mao, X. W. Guan, Biao Wu

    Research output: Contribution to journalArticlepeer-review

    11 Citations (Scopus)

    Abstract

    Using exact Bethe ansatz solutions, we show that a spin-down fermion immersed into a fully polarized spin-up Fermi sea with a weak attraction is dressed by the surrounding spin-up fermions to form the one-dimensional analog of a polaron. As the attraction becomes strong, the spin-down fermion binds with one spin-up fermion to form a tightly bound molecule. Throughout the whole interaction regime, a crossover from the polaron to a molecule state is fully demonstrated through exact results of the excitation spectrum, the effective mass, binding energy and kinetic energy. Furthermore, a clear distinction between the polaron and molecule is conceived by the probability distribution, single-particle reduced density matrix, and density-density correlations, which are calculated directly from the Bethe ansatz wave function. Such a polaron-molecule crossover presents a universal nature of an impurity immersed into a fermionic medium with an attraction in one dimension.

    Original languageEnglish
    Article number043645
    JournalPhysical Review A
    Volume94
    Issue number4
    DOIs
    Publication statusPublished - 27 Oct 2016

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