Logical qubit survival rose from below 90% to above 96% per error-correction cycle after University of Sydney and IBM Quantum redesigned circuits on IBM’s 156-qubit Heron r2 processor.
Mid-circuit measurements had been forcing nearby qubits to idle during feedback loops, and the team’s benchmarks identified that idling noise as a major source of logical gate errors in superconducting systems.
The workaround compacted execution schedules and physical circuit layout so data qubits spent less time exposed to thermal noise and phase decoherence during ancilla readouts.
Published in Nature Communications, the study is described as the first comprehensive quantitative benchmark of errors introduced directly by mid-circuit measurements, sharpening the path toward scalable quantum error correction and fault-tolerant quantum computing.
With rivals reporting 800x error reduction, can IBM's architectural fix for superconducting qubits truly close the quantum computing fidelity gap?
By solving the measurement bottleneck, what new challenge now becomes the main obstacle for fault-tolerant quantum computing?
Over 96% Logical Qubit Survival Achieved: A Major Leap Toward Fault-Tolerant Quantum Computing with IBM’s Heron r2
Overview
In June 2026, researchers from the University of Sydney and IBM achieved a major breakthrough by increasing logical qubit survival rates to over 96% on IBM’s 156-qubit Heron r2 superconducting processor. They tackled the problem of 'idling noise,' which causes errors during mid-circuit measurements, by redesigning quantum circuits and optimizing operation timing. This innovative engineering minimized the time qubits spent idle and exposed to noise, leading to a substantial reduction in error rates. The result marks a significant step toward more reliable and robust quantum computers, validated on advanced hardware with real experimental control.