Variational Tensor Wavefunctions for the Interacting Quantum Spin Hall Phase

Kavli Affiliate: Shenghan Jiang

| First 5 Authors: Yixin Ma, Shenghan Jiang, Chao Xu, ,

| Summary:

The quantum spin hall (QSH) phase, also known as the two-dimensional
topological insulator, hosts helical edge modes protected by time-reversal
symmetry. While first proposed as a band insulator, this phase can also be
realized in strongly-correlated systems, where the band theory fails to be a
good description. To simulate such a phase in realistic correlated models, it
is necessary to provide a generic variational ansatz for the interacting QSH
phase. In this work, we propose a framework to construct variational
wavefunctions for this phase using fermionic tensor network states. Based on
the exactly solvable model built from commuting projectors, we construct a
tensor representation of the fixed point wavefunction and extract a set of
tensor equations describing symmetry transformation rules on this tensor
network. From these equations, we derive the anomalous edge theory, which
indicates that such equations indeed give a complete description of the phase.
Solutions of tensor equations then give variational ansatz for the QSH phase.
Our method would serve as the first step to simulate this phase with tensor
algorithms in strongly-correlated systems.

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