Robust GHZ State Preparation via Majority-Voted Boundary Measurements

TL;DR

The paper introduces Group-Majority-Voting, a dynamic-circuit protocol that enhances GHZ state fidelity on noisy quantum hardware by using majority-voted boundary measurements to mitigate errors.

Contribution

It proposes a novel boundary measurement protocol that improves GHZ state preparation fidelity across various topologies and sizes on noisy quantum devices.

Findings

Group-MV achieves 2.4x higher fidelity than the Line Dynamic method.

It maintains fidelity within 3% of the unitary baseline.

The protocol generalizes to arbitrary GHZ sizes and topologies.

Abstract

Preparing high-fidelity Greenberger-Horne-Zeilinger (GHZ) states on noisy quantum hardware remains challenging due to cumulative gate errors and decoherence. We introduce Group-Majority-Voting (Group-MV), a dynamic-circuit protocol that partitions arbitrary coupling graphs, prepares local GHZ states in parallel, and fuses them via majority-voted mid-circuit measurements. The majority vote over redundant boundary links mitigates measurement errors that would otherwise propagate through classical feedforward. We evaluate Group-MV on simulated Heavy-hex and Grid topologies for 30 through 60 qubits under a realistic noise regime. Group-MV generalizes to arbitrary GHZ sizes on arbitrary coupling topologies, achieving 2.4x higher fidelity than the Line Dynamic method while tracking the unitary baseline within 3%.