IBM Reports Largest Entangled State to Date, Achieving 0.56 Fidelity on 120 Superconducting Qubits
Mohamed Abdel-Kareem2025-11-03T08:16:23-08:00IBM Quantum researchers have successfully prepared the largest Greenberger–Horne–Zeilinger (GHZ) state reported to date, consisting of 120 superconducting qubits. The experiment, detailed in a paper titled "Big cats: entanglement in 120 qubits and beyond," achieved a measured fidelity of 0.56(3), surpassing the 0.5 threshold required to confirm genuine multipartite entanglement across all qubits. The resource state was prepared on a fixed-frequency, tunable-coupler superconducting processor. The achievement was enabled by several specialized techniques within a novel compiler framework: Adaptive Compilation: The circuit was compiled adaptively to utilize the least noisy regions of the chip, maximizing error detection against non-uniform noise. Low-Overhead Error [...]