论文标题
2D中的相互作用拓扑量子化学:多体真实空间不变性
Interacting Topological Quantum Chemistry in 2D: Many-body Real Space Invariants
论文作者
论文摘要
非相互作用费米子的拓扑阶段已经通过它们的对称性进行了分类,最终是在现代电子带理论中(部分)从动量空间中获得的波函数拓扑。最近,真实的空间不变性(RSIS)提供了全球动量空间指数的空间局部描述。目前的工作将这种真实的空间分类概括为相互作用的2D状态。我们将多体局部RSI构建为一组对称算子的量子数,但它们与边界的选择无关。使用$ u(1)$粒子数,它们产生多体脆弱的拓扑指数,我们用来识别哪些单粒子脆弱状态在弱耦合时是多体拓扑或微不足道的。为此,我们构建了一个具有单粒子脆弱拓扑的确切可解决的哈密顿量,该拓扑通过强耦合而绝热地连接到微不足道的状态。然后,我们在周期性边界条件下定义了全局多体RSI。它们减少到频带理论极限中的Chern数量,但也识别出没有单粒子对应物的强稳定拓扑阶段。最后,我们表明,在描述该相的拓扑量子场理论中,多体局部RSI作为Wen-Zee项的量化系数。
The topological phases of non-interacting fermions have been classified by their symmetries, culminating in a modern electronic band theory where wavefunction topology can be obtained (in part) from momentum space. Recently, Real Space Invariants (RSIs) have provided a spatially local description of the global momentum space indices. The present work generalizes this real space classification to interacting 2D states. We construct many-body local RSIs as the quantum numbers of a set of symmetry operators on open boundaries, but which are independent of the choice of boundary. Using the $U(1)$ particle number, they yield many-body fragile topological indices, which we use to identify which single-particle fragile states are many-body topological or trivial at weak coupling. To this end, we construct an exactly solvable Hamiltonian with single-particle fragile topology that is adiabatically connected to a trivial state through strong coupling. We then define global many-body RSIs on periodic boundary conditions. They reduce to Chern numbers in the band theory limit, but also identify strongly correlated stable topological phases with no single-particle counterpart. Finally, we show that the many-body local RSIs appear as quantized coefficients of Wen-Zee terms in the topological quantum field theory describing the phase.