论文标题
远程相互作用的超平均旋转链中的量子相变
Quantum Phase Transitions in Long-Range Interacting Hyperuniform Spin Chains in a Transverse Field
论文作者
论文摘要
物质的超均匀状态的特征是对长波长密度波动的异常抑制。虽然大多数有趣的多体系统(如液体或无定形固体)提供了大多数有趣的超均匀性病例,但已证明具有某些长期相互作用的经典自旋链显示出相同的现象。众所周知,横向场ISING模型在零温度下显示了量子相变(QPT)。在横向磁场的量子效应下,经典的超明旋链有望失去其超均匀性。由于存在高度非平凡的远程相互作用,因此对这些情况的高精度模拟变得复杂。我们使用密度矩阵重新归一化组对这些系统进行广泛的分析,以研究相变的可能性和它们失去过度均匀性的机制。我们在超一样式旋转链中发现一阶QPT。这些无序的超一样式自旋链中相变的一个有趣特征是,根据参数值,即使超差异丢失,横向磁场的存在可能会显着导致基态的顺序增加。因此,在存在横向磁场的情况下,可以设计材料以靶向特定的新型量子行为。我们的数值研究表明,这些旋转链的显示不超过两个QPT。我们通过Jordan-Wigner映射进一步分析了远程相互作用的自旋链,这表明在成对相互作用的近似和平均场处理下,最多可以有两个QPT。基于这些数值和理论探索,我们认为这些自旋链在零温度下最多可以显示两个QPT。
Hyperuniform states of matter are characterized by anomalous suppression of long-wavelength density fluctuations. While most of interesting cases of disordered hyperuniformity are provided by complex many-body systems like liquids or amorphous solids, classical spin chains with certain long-range interactions have been shown to demonstrate the same phenomenon. It is well-known that the transverse field Ising model shows a quantum phase transition (QPT) at zero temperature. Under the quantum effects of a transverse magnetic field, classical hyperuniform spin chains are expected to lose their hyperuniformity. High-precision simulations of these cases are complicated because of the presence of highly nontrivial long-range interactions. We perform extensive analysis of these systems using density matrix renormalization group to study the possibilities of phase transitions and the mechanism by which they lose hyperuniformity. We discover first-order QPTs in the hyperuniform spin chains. An interesting feature of the phase transitions in these disordered hyperuniform spin chains is that, depending on the parameter values, the presence of transverse magnetic field may remarkably lead to increase in the order of the ground state as measured by the "$τ$ order metric," even if hyperuniformity is lost. Therefore, it would be possible to design materials to target specific novel quantum behaviors in the presence of a transverse magnetic field. Our numerical investigations suggest that these spin chains can show no more than two QPTs. We further analyze the long-range interacting spin chains via the Jordan-Wigner mapping, showing that under the pairwise interacting approximation and a mean-field treatment, there can be at most two QPTs. Based on these numerical and theoretical explorations, we conjecture that these spin chains can show a maximum of two QPTs at zero temperature.