低和中等填充硬核格点玻色子中的单杂质极化子
Single-impurity polarons in hard-core lattice bosons at low and intermediate fillings
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中文总结 AI 辅助
该研究通过无符号问题的worm算法量子蒙特卡罗模拟，探究二维硬核Bose-Hubbard浴中低和中等填充下的单杂质极化子，明确了耦合、填充及杂质迁移率对极化子性质和修饰云的影响。
中文摘要 AI 辅助
我们研究了二维硬核Bose-Hubbard浴中处于低和中等填充的单个移动杂质，并确定在从弱到强直至两分量硬核极限的杂质-浴耦合范围内，极化子 dressing（修饰）如何随浴填充变化。利用大规模无符号问题的worm算法量子蒙特卡罗模拟，我们从杂质格林函数中提取动量空间准粒子性质，并通过虚时间平均的以杂质为中心的关联函数解析伴随的实空间浴重排。我们还改变杂质跳跃t_imp，以评估在强耦合 regime（ regime 译为“区域”）中 mobility（ mobility 译为“迁移率”）降低如何修饰 dressing。对于每个耦合下可达到的填充，杂质保持为修饰后的准粒子，其基态能量、有效质量和残差随填充n_b平滑变化。在实空间中，n_b增加会增强短程耗尽，同时将主导响应移向杂质。在两分量硬核极限U_ib/t_b→∞时，所考虑范围内累积密度变形的长程恢复仅表现出弱填充依赖性，而短程核心指标仍会继续演化。我们的结果定量表征了关联可压缩格点浴中强修饰的极化子，并解析了填充和杂质迁移率如何修饰 dressing 云的近核心响应和空间范围。
英文摘要
We investigate a single mobile impurity in a two-dimensional hard-core Bose--Hubbard bath at low and intermediate fillings and determine how polaronic dressing evolves with bath filling for impurity--bath couplings ranging from weak to strong and ultimately to the two-component hard-core limit. Using large-scale, sign-problem-free worm-algorithm quantum Monte Carlo simulations, we extract momentum-space quasiparticle properties from the impurity Green's function and resolve the accompanying real-space bath rearrangement from an imaginary-time-averaged impurity-centered correlator. We also vary the impurity hopping $t_{\rm imp}$ to assess how reduced mobility modifies dressing in the strong-coupling regime. For the fillings accessible at each coupling, the impurity remains a dressed quasiparticle whose ground-state energy, effective mass, and residue vary smoothly with filling $n_{\rm b}$. In real space, increasing $n_{\rm b}$ strengthens the short-range depletion while shifting the dominant response toward the impurity. In the two-component hard-core limit $U_{\rm ib}/t_{\rm b}\!\to\!\infty$, the large-distance recovery of the cumulative density deformation exhibits only weak filling dependence over the range considered here, whereas short-range core indicators continue to evolve. Our results quantitatively characterize strongly dressed polarons in a correlated, compressible lattice bath and resolve how filling and impurity mobility modify the near-core response and spatial extent of the dressing cloud.
