论文标题
拓扑混乱参数
Topological Disorder Parameter
论文作者
论文摘要
我们引入了一个称为拓扑混乱参数(TDP)的多体拓扑不变性,以表征(2+1)d中的全局内部对称性的大图量子相。 TDP被定义为恒定校正,它出现在适用于连接的空间区域$ m $的部分对称转换的基础状态期望值中,其绝对值通常比例为$ \ exp(-αl+γ)$,其中$ l $是$ m $和$γ$的外膜。由操作员的拓扑量子场理论解释的动机,我们表明$ e^γ$可以与对称缺陷的量子维度有关,并在拓扑阶段的纠缠hamiltonian可以用(1+1)D形式场理论(CFT)描述时,为$γ$提供了一般公式。当对称性是间隙阶段的复制品的环状排列时,TDP的特殊情况等效于拓扑rényi纠缠熵。然后,我们在分析和数字上研究了拓扑阶段晶格模型的几个示例,尤其是当不满足CFT边缘理论的假设时。我们还考虑了Wen的Plaquette模型中部分翻译对称性的示例,并表明可以使用Edge CFT理解结果。我们的结果建立了一个新工具来检测量子拓扑顺序。
We introduce a many-body topological invariant, called the topological disorder parameter (TDP), to characterize gapped quantum phases with global internal symmetry in (2+1)d. TDP is defined as the constant correction that appears in the ground state expectation value of a partial symmetry transformation applied to a connected spatial region $M$, the absolute value of which scales generically as $\exp(-αl+γ)$ where $l$ is the perimeter of $M$ and $γ$ is the TDP. Motivated by a topological quantum field theory interpretation of the operator, we show that $e^γ$ can be related to the quantum dimension of the symmetry defect, and provide a general formula for $γ$ when the entanglement Hamiltonian of the topological phase can be described by a (1+1)d conformal field theory (CFT). A special case of TDP is equivalent to the topological Rényi entanglement entropy when the symmetry is the cyclic permutation of the replica of the gapped phase. We then investigate several examples of lattice models of topological phases, both analytically and numerically, in particular when the assumption of having a CFT edge theory is not satisfied. We also consider an example of partial translation symmetry in Wen's plaquette model and show that the result can be understood using the edge CFT. Our results establish a new tool to detect quantum topological order.