IBM and University of Chicago Achieve 70-Logical-Qubit Computation in 15 Minutes

Researchers from IBM and the University of Chicago announced on July 30, 2026 that a quantum computer completed an extremely complex computation in about 15 minutes, a task that would take an inestimable amount of time if handled by current leading classical simulation methods. The experiment also included a verification mechanism capable of assessing the accuracy of the quantum computation results. The findings were published on the arXiv preprint platform. The research team designed a new encoded quantum circuit that simultaneously achieved both computational speed and result verification. This is one of the largest logical quantum computing demonstrations reported to date, and the circuit design and experimental results have been made publicly available through the Quantum Advantage Tracker.

Result verification has long been a core obstacle in the field of quantum computing. In the past, Random Circuit Sampling (RCS) was commonly used as a benchmark to test whether quantum computers could surpass classical systems, but as computational difficulty increased, confirming the correctness of quantum computer outputs became increasingly challenging. This experiment adopted a more structured alternative to RCS that maintains equivalent computational difficulty while allowing dynamic error detection during computation. The researchers developed techniques to characterize the fidelity of complex quantum states in noisy environments, strengthening confidence in the quantum computer's ability to solve complex computational problems.

In this study, the researchers used 70 logical qubits to complete one of the largest quantum error correction demonstrations known to date. Logical qubits encode quantum information across multiple physical components, protecting computations from noise-induced errors. The system successfully performed 2,415 logical two-qubit operations and 468 logical T-gate operations. By encoding the circuit, the system reduced the effective logical error rate to one-tenth of the physical error rate, allowing the computation to maintain high fidelity while executing a large number of operations.

Reliable error correction and confidence in computational outputs are two necessary conditions for quantum systems to operate at larger scales. This experiment combined a problem intractable for classical computing with an accuracy assessment method, marking a step toward practical applications for quantum computing technology.