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arXiv 2104.14017cond-mat.quant-gascond-mat.mes-hallcond-mat.stat-mechcond-mat.str-elphysics.atom-ph
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二维强耦合玻色-费米混合体系的功能重整化群方法

Functional-renormalization-group approach to strongly coupled Bose-Fermi mixtures in two dimensions

Jonas von Milczewski, Félix Rose, Richard Schmidt

AI总结:

本文利用功能重整化群方法研究二维强耦合玻色-费米混合体系的相图,揭示极化子到分子转变、费米子复合体形成及强关联相变,并联系超冷原子与二维半导体中的普适物理。

摘要:

我们从理论上研究了具有吸引短程相互作用的强耦合二维玻色-费米混合体系随粒子密度变化的相图。我们关注玻色子与费米子之间束缚态尺寸远小于平均玻色子间距的极限情况,并发展了一种功能重整化群方法,以描述由扩展Fröhlich哈密顿量产生的束缚态物理。通过纳入三体关联,我们能够在玻色子密度趋于零的极端极限下重现二维费米气体中的极化子到分子转变。我们预言了频率和动量分辨的谱函数,并研究了三体关联对准粒子性质的影响。在有限玻色子密度下,我们发现当束缚态能量超过费米能量一个临界值时,费米子和玻色子可以形成具有明确费米面的费米子复合体。在超冷原子情形下,这些复合体构成由 dressed Feshbach 分子组成的费米海;而在原子级薄半导体情形下,则出现三激子液体。随着玻色子密度进一步增加,复合体的有效能隙减小,导致体系进入一种强关联相,其中极化子与分子自由度发生杂化。我们强调了二维半导体与超冷原子之间的普适联系,并讨论了在这些互补体系中进一步探索强耦合玻色-费米混合体系丰富结构的前景。

英文摘要:

We study theoretically the phase diagram of strongly coupled two-dimensional Bose-Fermi mixtures interacting with attractive short-range potentials as a function of the particle densities. We focus on the limit where the size of the bound state between a boson and a fermion is small compared to the average interboson separation and develop a functional-renormalization-group approach that accounts for the bound-state physics arising from the extended Fröhlich Hamiltonian. By including three-body correlations we are able to reproduce the polaron-to-molecule transition in two-dimensional Fermi gases in the extreme limit of vanishing boson density. We predict frequency- and momentum-resolved spectral functions and study the impact of three-body correlations on quasiparticle properties. At finite boson density, we find that when the bound-state energy exceeds the Fermi energy by a critical value, the fermions and bosons can form a fermionic composite with a well-defined Fermi surface. These composites constitute a Fermi sea of dressed Feshbach molecules in the case of ultracold atoms while in the case of atomically thin semiconductors a trion liquid emerges. As the boson density is increased further, the effective energy gap of the composites decreases, leading to a transition into a strongly correlated phase where polarons are hybridized with molecular degrees of freedom. We highlight the universal connection between two-dimensional semiconductors and ultracold atoms and we discuss perspectives for further exploring the rich structure of strongly coupled Bose-Fermi mixtures in these complementary systems.

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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