伪装自由费米子的关联与纠缠动力学
Correlation and entanglement dynamics of free fermions in disguise
浏览论文内容
中文总结 AI 辅助
通过映射到伪装自由费米子可解的量子淬火自旋链中，发展了广义吉布斯系综的准动量分布解析方法，并修正了基于准粒子图像的纠缠增长公式，数值验证表明局部观测量吻合良好但纠缠动力学存在微小偏差。
中文摘要 AI 辅助
我们研究了在可通过映射到伪装自由费米子求解的自旋链中，量子淬火后的非平衡动力学。这些模型具有所有能量本征值的指数简并性，这引发了关于描述可积系统非平衡性质的已有框架有效性的问题。我们提出两个主要结果。首先，我们发展了一种解析方法来计算表征广义吉布斯系综的准动量分布函数，并推导出一个解析公式来计算特殊可观测量的相应期望值。其次，我们基于准粒子图像，对纠缠增长的标准公式提出了一种修正，考虑到每个伪装费米子由于能量本征值的指数简并而携带额外的熵。我们针对不同的初始态和哈密顿参数，将我们的理论预测与数值张量网络计算进行了对比。对于局部可观测量，我们发现极好的一致性。对于纠缠动力学，我们发现微小偏差，表明我们的猜想仅近似正确。我们的结果代表了将可积系统非平衡的已有框架扩展到包含伪装自由费米子的模型的第一步。
英文摘要
We study the nonequilibrium dynamics following a quantum quench in spin chains that can be solved via a mapping to free fermions in disguise. These models feature an exponential degeneracy of all energy eigenvalues, raising the question of the validity of the established framework describing the properties of integrable systems out of equilibrium. We present two main results. First, we develop an analytic method to compute the quasi-momentum distribution function characterizing the generalized Gibbs ensemble, and derive an analytic formula to compute the corresponding expectation values for special observables. Second, we adapt the standard formula for the entanglement growth based on the quasi-particle picture, discussing how our constructions do not explicitly make use of the zero-energy auxiliary free fermions responsible of the exponential degeneracies. We test our theoretical predictions against numerical tensor-network computations for different initial states and Hamiltonian parameters. For the local observables, we find excellent agreement. For the entanglement dynamics, we find small deviations suggesting that the standard quasi-particle picture is only approximately correct for the initial state considered. Our results represent a first step towards the extension of the established framework of integrable systems out of equilibrium to models hosting free fermions in disguise.
