Characterizing Error Mitigation by Symmetry Verification in QAOA

Understand

Hardware errors are a major obstacle to demonstrating quantum advantage with the quantum approximate optimization algorithm (QAOA).

• Recently, symmetry verification has been proposed and empirically demonstrated to boost the quantum state fidelity, the expected solution quality, and the success probability of QAOA on a superconducting quantum processor.
• Symmetry verification uses parity checks that leverage the symmetries of the objective function to be optimized.
• We develop a theoretical framework for analyzing this approach under local noise and derive explicit formulas for fidelity improvements on problems with global $\mathbb{Z}_2$ symmetry.