BlueQubit Benchmarks Quantum Computational Advantage in Random-Circuit Sampling on IBM Nighthawk r2 Hardware
AI-summarised brief · reviewed before publication
Researchers from BlueQubit, EPFL and the XPRIZE Foundation demonstrated quantum computational advantage using random‑circuit sampling on IBM’s 120‑qubit ibm_phoenix processor, which employs the square‑lattice Nighthawk r2 architecture. The experiment ran forward RCS on 61 active qubits with native CZ gates, submitting circuits via standard Qiskit Runtime without custom calibration. At a depth of 36 cycles (918 CZ gates), the team achieved an XEB fidelity of approximately 2.3 × 10⁻³, generating 10⁶ samples in 19 seconds of QPU time. Reproducing the same output by tensor‑network rejection sampling on Oak Ridge’s Frontier supercomputer would require about 1.2 × 10²⁷ FLOPs, estimated as 110 years of exascale compute. The study also showed a per‑cycle fidelity of 0.872 on Nighthawk r2, a marked improvement over the earlier r1 generation, and confirmed resistance to classical “severing attacks,” underscoring the benchmark’s placement beyond the noise‑induced phase transition.
💡 Why It Matters
- · The result proves that commercially available superconducting hardware can now outperform the world’s fastest classical supercomputers on a specific sampling task, tightening the gap between research‑grade and production‑grade quantum advantage.
