BlueQubit Benchmarks Quantum Computational Advantage in Random-Circuit Sampling on IBM Nighthawk r2 Hardware

Researchers from BlueQubit, in collaboration with the Ecole Polytechnique Fédérale de Lausanne (EPFL) and the XPRIZE Foundation, have reported a demonstration of quantum computational advantage via random-circuit sampling (RCS) on commercial superconducting hardware.

In a preprint titled Quantum computational advantage in random-circuit sampling on IBM superconducting quantum computers, the team executed forward RCS on IBM Quantum’s 120-qubit ibm_phoenix processor, which uses the square-lattice Nighthawk r2 architecture.

Circuit Construction, Dual Fidelity Verification, and Contraction Complexity The experiment deployed a four-color brickwork schedule (cycling through matchings A, B, C, and D) across 102 active couplers, averaging 25.5 native CZ operations per cycle.

To evaluate vulnerabilities common to linear XEB metrics, the authors tested classical “severing attacks”—where cross-boundary couplers are deleted to simulate decoupled sub-circuits classically.

Technical details and experimental validation data are published on arXiv, with open-source circuits, execution scripts, and the full 106-sample dataset hosted on GitHub.