搜索

x
中国物理学会期刊

一维任意子Stark模型的多体局域化

CSTR: 32037.14.aps.74.20241615

Many-body localization of a one-dimensional anyon Stark model

CSTR: 32037.14.aps.74.20241615
PDF
HTML
导出引用
  • 本文研究了具有Stark势的一维相互作用任意子模型. 通过数值计算能谱统计、半链纠缠熵和粒子非平衡态占据数等来观测有限尺寸下的多体局域化现象. 随着线性势强度的增强, 系统的能谱统计分布从高斯系综向泊松系综过渡, 过渡区域的平均能级差比率表现为强烈依赖于统计角的非单调行为. 平均半链纠缠熵服从体积律到面积律转变且转变点对统计角有非单调依赖关系, 遍历相的半链纠缠熵随时间线性增长, 而在局域相中随时间呈对数增长, 其演化行为也与统计角有关. 最后随着线性势增大, 长时极限下粒子非平衡态占据数由零变为有限值, 有限值的大小与任意子统计角的取值有关, 这种演化行为进一步验证了任意子模型中统计角的重要性. 该研究结果为任意子系统中多体局域化的研究提供了新的视角.

     

    In this work, a one-dimensional interacting anyon model with a Stark potential in the finite size is studied. Using the fractional Jordan Wigner transformation, the anyons in the one-dimensional system are mapped onto bosons, which are described by the following Hamiltonian:
             \beginaligned \hatH^\textboson=-J\sum_j=1^L-1\left( \hatb_j^\dagger\hatb_j+1\mathrme^\mathrmi\theta \hatn_j+\mathrmh.c.\right)+\fracU2\sum_j=1^L\hatn_j\left( \hatn_j-1\right)+\sum_j=1^Lh_j\hatn_j,\;\;\;\;\;\;\;\;\;\endalignedwhere θ is the statistical angle, and the on-site potential is h_j=-\gamma\left(j-1\right) +\alpha\Big( \dfracj-1L-1\Big)^2 with γ representing the strength of the Stark linear potential and α denoting the strength of the nonlinear part. Using the exact diagonalization method, the spectral statistics, half-chain entanglement entropy and particle imbalance are numerically analyzed to investigate the onset of many-body localization (MBL) in this interacting anyon system, induced by increasing the linear potential strength. As the Stark linear potential strength increases, the spectral statistics transforms from a Gaussian ensemble into a Poisson ensemble. In the ergodic phase, except for θ = 0 and π, where the average value of the gap-ratio parameter \left\langle r\right\rangle\approx 0.53, due to the destruction of time reversal symmetry, the Hamiltonian matrix becomes a complex Hermit matrix and \left\langle r\right\rangle\approx 0.6. In the MBL phase, \left\langle r\right\rangle\approx 0.39, which is independent of θ. However, in the intermediate γ regime, the value of \left\langle r\right\rangle strongly depends on the choice of θ. The average of the half-chain entanglement entropy transforms from a volume law into an area law, which allows us to construct a θ-dependent MBL phase diagram. In the ergodic phase, the entanglement entropy S(t) of the half chain increases linearly with time. In the MBL phase, S(t) grows logarithmically with time, reaching a stable value that depends on the anyon statistical angle. The localization of particles in a quench dynamics can provide the evidence for the breakdown of ergodicity and is experimentally observable. It is observed that with the increase of γ, the even-odd particle imbalance changes from zero to non-zero values in the long-time limit. In the MBL phase, the long-time average value of the imbalance is dependent on the anyon statistical angle θ. From the Hamiltonian \hatH^\textboson, it can be inferred that the statistical behavior of anyon system equally changes the hopping interactions in boson system, which is a many-body effect. By changing the statistical angle θ, the many-body interactions in the system are correspondingly changed. And the change of the many-body interaction strength affects the occurrence of the MBL transition, which is also the reason for MBL transition changing with the anyon statistical angle θ. Our results provide new insights into the study of MBL in anyon systems and whether such phenomena persist in the thermodynamic limit needs further discussing in the future.

     

    目录

    /

    返回文章
    返回
    Baidu
    map