Quenches and dynamical phase transitions in a non-integrable quantum Ising model
Quenches and dynamical phase transitions in a non-integrable quantum Ising model
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DOI：
10.1103/physrevb.92.104306
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发表时间：
2015-06
影响因子：
3.7
通讯作者：
Shraddha Sharma;S. Suzuki;A. Dutta
中科院分区：
文献类型：
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作者：
Shraddha Sharma;S. Suzuki;A. Dutta
我们研究了一维横向伊辛链与最近邻反铁磁相互作用在纵向场的存在下，使模型不可积的淬火动力学。自旋链的动力学研究后，缓慢（其特征在于由速率）或突然淬火的纵向场;剩余能量，数值计算得到的使用t-DMRG计划，发现满足分析预测的标度关系在这两种情况下。然而，分析的时间演变的Loschirt重叠，我们发现不同的可能性的存在（或不存在）的动力学相变（DPTs）表现在非解析的速率函数。即使该模型是不可积的，也有{周期性}的DPT发生时，该系统是缓慢斜跨量子临界点（QCP），而不是铁磁（FM）版本的模型;这个数值发现定性地解释了映射到一个有效的可积自旋模型，这是适当的描述这种缓慢的淬火的原始模型。此外，关于突然猝灭，我们的数值计算结果表明，在某些情况下，DPT可以存在，甚至当自旋链在同一相位内，甚至QCP猝灭，而在其他一些情况下，他们完全消失，甚至在淬火后，通过QCP。这些观察使我们得出结论，这是在基态的性质的变化，决定了DPT的存在下突然淬火。
We study quenching dynamics of a one-dimensional transverse Ising chain with nearest neighbor antiferromagentic interactions in the presence of a longitudinal field which renders the model non-integrable. The dynamics of the spin chain is studied following a slow (characterized by a rate) or sudden quenches of the longitudinal field; the residual energy, as obtained numerically using a t-DMRG scheme, is found to satisfy analytically predicted scaling relations in both the cases. However, analyzing the temporal evolution of the Loschmidt overlap, we find different possibilities of the presence (or absence) of dynamical phase transitions (DPTs) manifested in the non-analyticities of the rate function. Even though the model is non-integrable, there are {periodic} occurrences of DPTs when the system is slowly ramped across the quantum critical point (QCP) as opposed to the ferromagnetic (FM) version of the model; this numerical finding is qualitatively explained by mapping the original model to an effective integrable spin model which is appropriate for describing such slow quenches. Furthermore, concerning the sudden quenches, our numerical results show that in some cases, DPTs can be present even when the spin chain is quenched within the same phase or even to the QCP while in some other situations they completely disappear even after quenching across the QCP. These observations lead us to the conclusion that it is the change in the nature of the ground state that determines the presence of DPTs following a sudden quench.