Conditionally Rigorous Mitigation of Multiqubit Measurement Errors

Several techniques have been recently introduced to mitigate errors in near-term quantum computers without the overhead required by error correcting codes. While most of focus has on gate errors, measurement are significantly larger than some platforms. A widely used transition matrix mitigation (TMEM) technique uses measured probabilities between initial and final classical states correct subsequently data. However from a rigorous perspective, noisy should be calibrated with perfectly prepared states, presence any state-preparation corrupts resulting mitigation. Here we develop technique, conditionally TMEM, that is not sensitive thus avoids this limitation. We demonstrate importance for high-precision foundations experiments measuring Mermin polynomials IBM Q superconducting qubits. An extension allows one both (SPAM) expectation values as well; illustrate giving protocol fully SPAM-corrected process tomography.