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arXiv 1702.05097cond-mat.quant-gasquant-ph
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光晶格中的自旋杂质

Mobile Spin Impurity in an Optical Lattice

C. W. Duncan, F. F. Bellotti, P. Öhberg, N. T. Zinner, M. Valiente

摘要:

本文研究了光晶格中自旋为1/2的费米气体中的费米极化子问题,考虑了接触相互作用的强排斥和一维极限。在这个极限下,不可能有类似极化子的行为,物理学上是一个磁振子或杂质。当系统的电荷自由度被冻结时,杂质自旋的紧束缚哈密顿量呈现出一种有趣的结构,这种结构强烈依赖于晶格势的填充因子。这种填充依赖性也转移到两个磁振子的情况下和重要的自旋平衡的情况下的相互作用的性质。在低填充,直到近单位填充,单个杂质哈密顿忠实地再现了单带,准均匀紧束缚问题。随着填充的增加和周期性势的单粒子谱的第二带逐渐填充,在低能量下的杂质哈密顿量描述了被困在多阱势中的单粒子。有趣的是,一旦前两个能带被完全填满,杂质哈密顿量就是Su-Schrieffer-Heeger模型的近乎完美的实现。我们的研究,这远远超出了单带近似,即哈伯德模型,铺平了道路,实现相互作用的凝聚态物理的一维模型。

英文摘要:

We investigate the Fermi polaron problem in a spin-1/2 Fermi gas in an optical lattice for the limit of both strong repulsive contact interactions and one dimension. In this limit, a polaronic-like behaviour is not expected, and the physics is that of a magnon or impurity. While the charge degrees of freedom of the system are frozen, the resulting tight-binding Hamiltonian for the impurity's spin exhibits an intriguing structure that strongly depends on the filling factor of the lattice potential. This filling dependency also transfers to the nature of the interactions for the case of two magnons and the important spin balanced case. At low filling, and up until near unit filling, the single impurity Hamiltonian faithfully reproduces a single-band, quasi-homogeneous tight-binding problem. As the filling is increased and the second band of the single particle spectrum of the periodic potential is progressively filled, the impurity Hamiltonian, at low energies, describes a single particle trapped in a multi-well potential. Interestingly, once the first two bands are fully filled, the impurity Hamiltonian is a near-perfect realisation of the Su-Schrieffer-Heeger model. Our studies, which go well beyond the single-band approximation, that is, the Hubbard model, pave the way for the realisation of interacting one-dimensional models of condensed matter physics.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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