IBM and University of Chicago Achieve Trusted Quantum Advantage with 70 Logical Qubits, Outperforming Classical Computation

August 2, 2026

IBM USA

Overview

IBM and University of Chicago researchers have demonstrated quantum advantage in trusted computation, executing complex tasks using 70 logical qubits in approximately 15 minutes, a feat practically impossible for classical supercomputers. This breakthrough was achieved through a novel construction of encoded quantum circuits using doped Clifford sampling and spacetime codes, ensuring the accuracy of the quantum computation. The ability to perform and verify such computations marks a significant step towards practical fault-tolerant quantum computing, dramatically expanding the scope of problems quantum computers can reliably address.

In Depth

Key Findings

IBM and University of Chicago researchers have successfully demonstrated ‘quantum advantage’ by performing reliable computations with 70 logical qubits that are beyond the reach of leading classical simulation methods. This landmark achievement, completed in approximately 15 minutes, not only showcases the quantum computer’s superior computational power over traditional supercomputers for specific complex tasks but also crucially provides methods to guarantee the accuracy of these quantum results. This dual demonstration of computational superiority and verifiable reliability is a significant leap towards practical and trustworthy quantum computing applications.

Technical / Clinical Details

The core of this breakthrough lies in the novel construction of encoded quantum circuits, utilizing doped Clifford sampling and spacetime codes. These techniques enabled the creation of stable ‘logical qubits’ from inherently noisy physical qubits, drastically improving the fidelity of quantum operations. The 70 logical qubits supported 2,415 logical two-qubit operations and 468 logical T-gates, achieving high circuit fidelity with a significantly reduced logical error rate. Logical qubits, designed to mitigate errors by encoding information redundantly across multiple physical qubits, represent a crucial step towards fault-tolerant quantum systems. This demonstration stands as one of the largest logical quantum computing experiments to date.

Background & Context

Quantum advantage signifies the point where a quantum computer surpasses classical computers for certain computational problems, but verifying the reliability of these complex quantum computations has been a persistent challenge. Prior demonstrations of quantum advantage often faced critiques regarding the difficulty of verifying results. This research addresses that by establishing new methods for ‘trusted quantum computation,’ thereby solidifying the practical utility of quantum advantage. It lays a critical foundation for quantum computing to move beyond theoretical demonstrations into real-world scientific and industrial applications, impacting fields from chemistry to materials science.

Strategic Significance & Outlook

This advance is instrumental in accelerating the development of fault-tolerant quantum computers. The increased scale and reliability of logical qubits bring complex simulations—such as those for novel materials, drug discovery, and advanced chemistry—closer to realization. IBM projects that commercially valuable quantum computations could be achieved by 2029, with this milestone serving as a critical stepping stone. The ability to perform and verify complex calculations that would take classical supercomputers millennia suggests a future where quantum systems complement and extend human scientific capability, unlocking solutions to currently intractable problems across various sectors globally.

Source: https://www.ibm.com/quantum/blog/quantum-advantage

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