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arXiv 2007.16128cond-mat.str-elquant-ph
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横场中长程各向异性$XY$ -链的量子临界性和激发

Quantum criticality and excitations of a long-range anisotropic $XY$-chain in a transverse field

P. Adelhardt, J. A. Koziol, A. Schellenberger, K. P. Schmidt

摘要:

研究了具有长程相互作用的一维量子磁体在铁磁和反铁磁情况下,在横场中各向异性XY模型的高场极化相位.而对于各向同性长程XY模型的极限情况,我们可以解析地提取基本的一个准粒子色散,并以数值方式定量地计算两个准粒子的激发能,对于长程伊辛极限以及在中间区域,我们使用白图上的微扰连续么正变换结合经典的图嵌入的蒙特卡罗模拟来提取高-在热力学极限下的级数展开。这使我们能够确定高场极化相位的量子临界击穿通过分析间隙闭合,包括相关的临界指数和乘法对数校正。此外,对于铁磁各向同性XY模型,我们用玻色子量子场论解析地确定了临界指数$z$和$ν$.

英文摘要:

The critical breakdown of a one-dimensional quantum magnet with long-range interactions is studied by investigating the high-field polarized phase of the anisotropic XY model in a transverse field for the ferro- and antiferromagnetic case. While for the limiting case of the isotropic long-range XY model we can extract the elementary one quasi-particle dispersion analytically and calculate two quasi-particle excitation energies quantitatively in a numerical fashion, for the long-range Ising limit as well as in the intermediate regime we use perturbative continuous unitary transformations on white graphs in combination with classical Monte Carlo simulations for the graph embedding to extract high-order series expansions in the thermodynamic limit. This enables us to determine the quantum-critical breakdown of the high-field polarized phase by analyzing the gap-closing including associated critical exponents and multiplicative logarithmic corrections. In addition, for the ferromagnetic isotropic XY model we determined the critical exponents $z$ and $ν$ analytically by a bosonic quantum-field theory.

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