IBM Quantum

Google Quantum AI operates from Santa Barbara, California. In late 2024, its Willow chip demonstrated below-threshold quantum error correction for the first time — the most significant QEC milestone to date. In October 2025, Google acquired MIT-founded Atlantic Quantum, adding its modular superconducting chip stack (co-located qubits and cryogenic control electronics) to accelerate scaling toward large-scale error-corrected systems. Google's open-source Cirq framework is widely used for circuit-level quantum programming.

Rigetti is a publicly traded pure-play quantum computing company that designs and manufactures superconducting quantum processors in its own fabrication facility — one of only a few quantum companies with in-house fab capability. Its current Ankaa-2 system (84 qubits) uses tunable couplers and a square lattice for 98% median two-qubit gate fidelity. Rigetti also sells QPUs directly through its Novera product line, and offers cloud access via Amazon Braket and Azure Quantum. In collaboration with Riverlane, it demonstrated real-time low-latency quantum error correction in 2024.

Formed from the 2021 merger of Honeywell Quantum Solutions and Cambridge Quantum Computing, Quantinuum leads the world in logical qubit count and trapped-ion fidelity. Its Helios system (launched November 2025) offers 98 physical and 48 logical qubits using barium atoms, and is available via cloud and on-premises installation. Early users include JPMorgan Chase, SoftBank, Amgen, and BMW. Quantinuum was valued at $10 billion as of 2025 and is backed by Honeywell, which retains majority ownership. It also develops TKET, a widely-used open-source quantum compiler.

IonQ is the first publicly traded pure-play quantum computing company. In 2025, IonQ executed the largest acquisition spree in quantum history: Oxford Ionics for $1.075B (June 2025), a controlling stake in ID Quantique for quantum networking (May 2025), and SkyWater Technology semiconductor foundry for $1.8B (January 2026). The combined entity targets 256 physical qubits at 99.99% accuracy and 2 million physical qubits by 2030. Systems available on Amazon Braket, Azure Quantum, and Google Cloud.