Spontaneous Parity Violation in a Quantum Spin Chain

TL;DR

This paper demonstrates spontaneous parity violation in a one-dimensional quantum spin chain model with SU(3) gauge symmetry, revealing a degenerate ground state and a topological order parameter.

Contribution

It introduces a novel spin chain model exhibiting spontaneous parity breaking and analytically characterizes its topological order.

Findings

Ground state spontaneously violates parity

Model has a two-fold degenerate ground state

Presence of a non-zero topological string order parameter

Abstract

We report on a spontaneous breakdown of parity in the ground state of a spin Hamiltonian involving nearest-neighbor interactions. This occurs for a one-dimensional model where spins transform under the gauge field representation of QCD, the eight-dimensional adjoint representation of SU(3). The ground state spontaneously violates parity and is two-fold degenerate. In addition, the model possesses a non-vanishing topological string order parameter which we explicate analytically.