arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1205.2674quant-phcond-mat.other
收藏

具有长程相互作用的无限自旋链的改进数值方法

Improved numerical methods for infinite spin chains with long-range interactions

V. Nebendahl, W. Dür

摘要:

我们提出了几种改进的无限矩阵乘积态(iMPS)算法,用于寻找具有长程相互作用的一维量子系统的基态。作为一个主要的新成分,我们介绍了叠加多优化(SMO)方法,它允许一个有效的优化指数许多MPS的不同长度在不同的网站都在一个步骤。因此,该算法变得免受由自发破坏的平移不变性引起的位置相关效应的影响。到目前为止,如果没有系统平移对称性的先验知识,这些都是iMPS算法收敛的主要障碍。此外,我们研究了一些更通用的方法来加快计算速度和提高收敛性,这在更广泛的背景下也可能是部分有趣的。作为一个更特殊的问题,我们也期待到平移不变的状态接近不变性制动相变,并显示如何避免收敛到错误的局部极小这样的系统。最后,我们将新的方法应用于具有长程相互作用的极性玻色子。我们计算了几个详细的魔鬼阶梯,并给出了相应的相图,研究了一些超固体的性质。

英文摘要:

We present several improvements of the infinite matrix product state (iMPS) algorithm for finding ground states of one-dimensional quantum systems with long-range interactions. As a main new ingredient we introduce the superposed multi-optimization (SMO) method, which allows an efficient optimization of exponentially many MPS of different length at different sites all in one step. Hereby the algorithm becomes protected against position dependent effects as caused by spontaneously broken translational invariance. So far, these have been a major obstacle to convergence for the iMPS algorithm if no prior knowledge of the systems translational symmetry was accessible. Further, we investigate some more general methods to speed up calculations and improve convergence, which might be partially interesting in a much broader context, too. As a more special problem, we also look into translational invariant states close to an invariance braking phase transition and show how to avoid convergence into wrong local minima for such systems. Finally, we apply the new methods to polar bosons with long-range interactions. We calculate several detailed Devil's Staircases with the corresponding phase diagrams and investigate some supersolid properties.

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。

↑