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arXiv 1912.09443cond-mat.str-elcond-mat.quant-gas
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一维无序玻色-哈伯德模型中单粒子观的多体局域化

Many-body localization from a one-particle perspective in the disordered 1D Bose-Hubbard model

Miroslav Hopjan, Fabian Heidrich-Meisner

摘要:

利用精确对角化方法,对具有在位无序的一维玻色-哈伯德链进行数值研究。我们的工作的主要重点是从单粒子的角度来描述这个模型中的Fock空间局部化。为此,我们计算了多体本征态的单粒子密度矩阵。我们表明,自然轨道(本征态的OPDM)的遍历阶段和实空间本地化时,进入MBL阶段的扩展。此外,占据的自然轨道的分布可以被用来作为在各自的基础上的Fock空间本地化的措施。与以前的研究相一致,我们观察到的签名时,增加无序强度的遍历到多体局域化(MBL)制度的过渡。我们进一步证明,福克空间的本地化,虽然较弱,也明显存在于物理密度的分布在MBL制度,无论是软,硬核玻色子。此外,物理粒子的密度的完全分布提供了一个单粒子测量的遍历MBL过渡的检测,可以直接在超冷气体的实验中访问。

英文摘要:

We numerically investigate 1D Bose-Hubbard chains with onsite disorder by means of exact diagonalization. A primary focus of our work is on characterizing Fock-space localization in this model from the single-particle perspective. For this purpose, we compute the one-particle density matrix (OPDM) in many-body eigenstates. We show that the natural orbitals (the eigenstates of the OPDM) are extended in the ergodic phase and real-space localized when one enters into the MBL phase. Furthermore, the distributions of occupations of the natural orbitals can be used as measures of Fock-space localization in the respective basis. Consistent with previous studies, we observe signatures of a transition from the ergodic to the many-body localized (MBL) regime when increasing the disorder strength. We further demonstrate that Fock-space localization, albeit weaker, is also evidently present in the distribution of the physical densities in the MBL regime, both for soft- and hardcore bosons. Moreover, the full distribution of the densities of the physical particles provides a one-particle measure for the detection of the ergodic-MBL transition which could be directly accessed in experiments with ultra-cold gases.

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