We present a method for deriving bulk and edge invariants for interacting, many-body localized Floquet systems in two spatial dimensions. This method is based on a general mathematical object which we call a flow. As an application of our method, we derive bulk invariants for Floquet systems without symmetry, as well as for systems with $U(1)$ symmetry. We also derive new formulations of previously known single-particle and many-body invariants. For bosonic systems without symmetry, our invariant gives a bulk counterpart of the rational-valued GNVW index $\frac{p}{q}$ quantifying transport of quantum information along the edge.

中文翻译：

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二维交互 Floquet 系统的体边界对应

我们提出了一种方法，用于在两个空间维度上为相互作用的多体局部化 Floquet 系统推导体积和边缘不变量。此方法基于我们称为流的一般数学对象。作为我们方法的一个应用，我们为没有对称性的 Floquet 系统以及具有 $U(1)$ 对称性的系统推导出体不变量。我们还推导出以前已知的单粒子和多体不变量的新公式。对于没有对称性的玻色子系统，我们的不变量给出了有理值 GNVW 指数 $\frac{p}{q}$ 的体积对应物，用于量化量子信息沿边缘的传输。