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  • Open Access

Readout Error Mitigation for Mid-Circuit Measurements and Feedforward

Jin Ming Koh1,*, Dax Enshan Koh2,3,4,†, and Jayne Thompson5,6,3,‡

  • *Contact author: jkoh@fas.harvard.edu
  • †Contact author: dax_koh@a-star.edu.sg
  • ‡Contact author: thompson.jayne2@gmail.com
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PRX Quantum 7, 010317 – Published 26 January, 2026

DOI: https://doi.org/10.1103/cj89-4h5t

Abstract

Current quantum computing platforms suffer from readout errors, where faulty measurement outcomes are reported by the device. These errors are particularly harmful in quantum programs that rely on branch statements, where operations in later parts of the program are dynamically determined by mid-circuit measurements. We propose a general protocol for mitigating mid-circuit measurement errors. Our solution works for any number of mid-circuit measurement and feedforward layers without increasing circuit depth or two-qubit gate counts, is efficient under structural assumptions on error channels, and is suitable for immediate application on noisy intermediate-scale quantum devices. We experimentally demonstrate up to a ∼60% reduction in error on superconducting quantum processors across several practically relevant feedforward circuits, including dynamic qubit resets, shallow-depth Greenberger–Horne–Zeilinger state preparation, and multistage quantum teleportation. This work paves the way for more error-resilient adaptive quantum circuits, crucial for current and future quantum computing applications.

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Physics Subject Headings (PhySH)

Popular Summary

Recent advances in quantum computing have enabled mid-circuit measurements and feedforward, allowing real-time adjustments to quantum circuits based on earlier measurement outcomes. This capability is essential for a wide range of applications, such as measurement-based quantum computing, state and gate teleportation, circuit stitching and knitting, quantum metropolis sampling, among many others.

As powerful as this technology is, it has an Achilles heel: practical quantum devices often suffer from significant levels of readout noise, wherein measurement outcomes are inaccurately identified and reported. These mid-circuit readout errors not only corrupt measurement data but also lead to the execution of incorrect operations later in the computation. Such a significant issue may seem insurmountable: How do we mitigate errors that cause us to go down an entirely incorrect branch of our program?

Here we give a protocol for mitigating such mid-circuit measurement errors on circuits with feedforward, allowing us to recover the correct computational results (i.e., expectation values) in spite of these errors. Our method is efficient, imposing no additional gate depth or qubit requirements—crucial factors for practicality on current and near-term devices. Experimental results on superconducting quantum processors demonstrate up to 60% improvement in outcomes for tasks like qubit resets, entangled state preparation, and quantum teleportation.

This brings the window for demonstrating important quantum primitives and algorithms on quantum processors forward. We anticipate our scheme to be a useful building block in allowing the execution of complex programs on near-term and future quantum devices.

Article Text

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PRX Quantum 7, 010317– Published 26 January, 2026
  • Received 13 August 2024
  • Revised 30 September 2025
  • Accepted 10 December 2025
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