2026-07-30 シカゴ大学（UChicago）
IBM and researchers from the University of Chicago announced a demonstration in quantum computing that meets the fundamental criteria for “quantum advantage”—the point where quantum computers can be confirmed to have outperformed classical computers.Photo courtesy IBM
＜関連情報＞
- https://news.uchicago.edu/story/ibm-uchicago-demonstrate-quantum-advantage-outperforming-traditional-computers-quantum
- https://arxiv.org/abs/2607.25941
検証可能な高忠実度でハード回路をサンプリングする
Sampling hard circuits with verifiably high fidelity
Simon Martiel, Jay-U Chung, Alireza Seif, Soumik Ghosh, Ian Hincks, Abhinav Deshpande, Bill Fefferman, Jay M. Gambetta, Ali Javadi-Abhari
arXiv Submitted on 28 Jul 2026
DOI:https://doi.org/10.48550/arXiv.2607.25941
Sampling-based proposals are prominent candidates for demonstrating quantum computations beyond the reach of classical supercomputers. However, it has been difficult to combine their complexity-theoretic hardness with two capabilities needed for scalable quantum computing more generally: suppressing hardware errors, and verifying the quantum computation itself. Here we address both issues by introducing structured circuits, which, in addition to provable hardness guarantees, admit an encoding in a quantum code. This allows us to simultaneously reach high fidelities at high circuit depths, and to certify an experimental fidelity via the circuit structure and measurement of code syndromes. The resulting certificate is device dependent, but requires substantially weaker noise assumptions than existing fidelity proxy benchmarks. We demonstrate our proposal with a 70-qubit, depth-70 Clifford circuit doped with 468 T gates. We use a total of 97 physical qubits to encode this computation in spacetime codes, effectively suppressing gate error rates by 10× after syndrome post-selection, and yielding a state with a fidelity lower bound of 0.284 with 95% confidence. Our construction is a systematic method for promoting a stabilizer state to a magic state while keeping an error-detected fidelity certificate.
