Topological order in the pseudogap metal

TL;DR

This paper investigates the topologically ordered Higgs phase in a gauge theory of fluctuating antiferromagnetism, comparing theoretical calculations with numerical methods to reveal signatures of topological order in the pseudogap phase of the Hubbard model.

Contribution

It introduces a topologically ordered Higgs phase in a gauge theory framework and connects it with observable features in the pseudogap phase of the Hubbard model.

Findings

Good agreement between gauge theory and numerical methods in spectral functions.

Lines of zeros in Green's function indicate topological order.

Derived a non-perturbative Luttinger theorem for the Higgs phase.

Abstract

We compute the electronic Green's function of the topologically ordered Higgs phase of a SU(2) gauge theory of fluctuating antiferromagnetism on the square lattice. The results are compared with cluster extensions of dynamical mean field theory, and quantum Monte Carlo calculations, on the pseudogap phase of the strongly interacting hole-doped Hubbard model. Good agreement is found in the momentum, frequency, hopping, and doping dependencies of the spectral function and electronic self-energy. We show that lines of (approximate) zeros of the zero-frequency electronic Green's function are signs of the underlying topological order of the gauge theory, and describe how these lines of zeros appear in our theory of the Hubbard model. We also derive a modified, non-perturbative version of the Luttinger theorem that holds in the Higgs phase.