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Mitigating errors in state preparation and measurement with noncomputational states

Conrad J. Haupt1,2, Almudena Carrera Vazquez1, Laurin E. Fischer1,3, Stefan Woerner1, and Daniel J. Egger1,*

  • *Contact author: deg@zurich.ibm.com
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Phys. Rev. Applied 25, 024079 – Published 25 February, 2026

DOI: https://doi.org/10.1103/jv9h-spzw

Abstract

Error mitigation has enabled quantum computing applications with more than a hundred qubits and deep circuits. Many error mitigation methods are noise-aware, relying on a faithful characterization of the noise channels of the hardware. However, fundamental limitations lead to unlearnable degrees of freedom of the underlying noise models when considering qubits. Here, we show how to leverage noncomputational states as an additional resource to learn state-preparation errors in superconducting qubits. This allows one to fully constrain the noise models. We can thus independently and accurately mitigate state-preparation errors, gate errors, and measurement errors. Our proposed method is also applicable to dynamic circuits with midcircuit measurements. This work opens the door to improved error mitigation for measurements, both at the end of the circuit and midcircuit.

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Phys. Rev. Applied 25, 024079– Published 25 February, 2026
  • Received 30 June 2025
  • Revised 3 December 2025
  • Accepted 8 December 2025
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