Drift-resilient mid-circuit measurement error mitigation for dynamic circuits

Abstract: Quantum Error mitigation (QEM) for dynamic circuits, i.e. those incorporating mid-circuit measurement and feedforward, is important for two key reasons. First, quantum error correction (QEC) circuit are instances of dynamic circuits, and therefore a compatible QEM can extend circuit depth and address errors that QEC struggles with. Second, recent studies show dynamic circuits can significantly outperform purely unitary ones. However, mid-circuit measurement errors remain a major bottleneck. Current solutions rely on readout noise characterization, which is vulnerable to temporal noise drifts. We propose a drift-resilient protocol for addressing preparation, mid-circuit, and terminating measurement errors without requiring calibration or characterization. One scheme uses parity checks of repeated measurements (suitable for superconducting qubits), while the other leverages reset and feedforward (suitable for trapped ions). We demonstrate our methods experimentally on IBMQ and Quantinuum hardware. Combined with the Layered-KIK gate error mitigation protocol, this readout mitigation approach enables 'End-to-end' mitigation for dynamic circuits, which can improve the outcomes of QEC experiments. Other applications of the presented methods include a faster alternative to gate-set tomography and diagnostics of defective qubits during the execution of the target algorithm.