论文标题
分区协议中的连接相关性：案例研究及以后
Connected correlations in partitioning protocols: a case study and beyond
论文作者
论文摘要
在不均匀量子淬灭中局部松弛的假设允许渐近地通过称为广义流体动力学（GHD）的流体动力学参数来渐近地计算局部可观察到的期望值。在这项工作中，我们正式解决了何时可观察到的问题是``本地足够''，以使用分区协议的操场和非相互作用的时间演变来由GHD描述。我们表明，在二次哈密顿量下演变的任何状态都可以通过一组脱钩的动力场来描述，以便可以通过对根密度的时空依赖性概括来识别其中一个场。通过研究对每个磁场的连接自旋相关的贡献，我们得出了仅使用根密度来描述可观察到的位置条件。这显示了旨在描述仅在根密度（例如GHD）和高斯化发生所需的局部条件的渐近性的流体动力学方法方面的有效性。
The assumption of local relaxation in inhomogeneous quantum quenches allows to compute asymptotically the expectation value of local observables via hydrodynamic arguments known as generalized hydrodynamics (GHD). In this work we address formally the question of when an observable is ``local enough'' to be described by GHD using the playground of partitioning protocols and non-interacting time evolution. We show that any state evolving under a quadratic Hamiltonian can be described via a set of decoupled dynamical fields such that one of those fields can be identified with a space-time-dependent generalisation of the root density. By studying the contribution to a connected spin correlation of each of those fields independently, we derive the locality conditions under which an observable can be described using the root density only. That shows both the regime of validity for hydrodynamic approaches that aim at describing the asymptotic value of observables in term of the root density only, such as GHD, and the locality conditions necessary for Gaussianification to occur.
