Parity measurement via ancillary RF-SQUIDs for superconducting flux qubit quantum annealers*

Next generation quantum annealing (QA) will likely rely on error suppression codes. Proposals for error suppression in QA often use energy penalties [Quantum Inf. Process. 16: 89 (2017)] or parity measurements [Phys.Rev.A 95, 032317 (2017)]. We propose a device to do parity measurements in quantum annealers based on flux qubits. This device consists of two RF-SQUIDs coupled to the measured qubits. We simulate the quantum measurement process, including realistic implementation effects. We consider generalizations of this approach to higher-order parity measurements. We also present a different approach based on symmetrical coupling of a flux readout device, designed to measure parity information. Prospects for experimental demonstration are discussed.