Generation of long-range entanglement enhanced by error detection

Significant progress has been made in experimental demonstrations of quantum error correction (QEC), but the resource overhead required to achieve true fault-tolerant quantum computing remains substantial. In this talk, we demonstrate that strategic application of QEC primitives can yield significant net benefits to quantum computation with modest overhead on a superconducting processor. We first present a novel protocol for long-range CNOT gates that relies on a unitarily-prepared Greenberger-Horne-Zeilinger (GHZ) state as well as a unitary disentangling step. Our protocol reduces the sensitivity to readout errors relative to the existing measurement-based protocol, and enables efficient error detection. We demonstrate that our protocol achieves state-of-the-art gate fidelities of over 84% across up to 40 lattice sites, significantly and consistently outperforming the measurement-based protocol. We then further explore the advantages of applying QEC primitives by generating GHZ states while detecting errors through sparse stabilizer measurements utilizing ancillas. Employing this technique, we generate a 75-qubit GHZ state exhibiting genuine multipartite entanglement, the largest reported to date. The generation requires no more than 9 ancillary qubits and the discarded fraction of samples due to errors grows no higher than 78%. The state fidelity and discard fraction are investigated as a function of the number of ancillas. We discuss strategies on how to apply QEC primitives to ensure a net benefit.