Quantinuum

Type: Company (Quantum computing) Formed from: Merger of Honeywell Quantum Solutions + Cambridge Quantum (2021)

Quantinuum demonstrated in March 2026 the most qubit-efficient break-even crossing to date: 94 error-protected logical qubits using only 98 physical qubits on a trapped-ion processor, powered by iceberg codes. Logical gate error rates reached ~1 in 10,000 and GHZ fidelity hit 95% across the full 94-qubit system. This is the trapped-ion counterpart to IBM's superconducting qLDPC story.

Key Contributions

• 94 logical qubits / 98 physical — radically lower overhead than surface codes. (Quantinuum)
• Iceberg codes — concatenated detection/correction scheme where many logical qubits sit beneath a small error-checking layer. (Quantinuum)
• Beyond break-even — encoded operations outperform the underlying physical hardware. (Quantinuum)
• 95% GHZ state fidelity — across 94 logical qubits. (Quantinuum)

Caveats

• Current demonstrations rely on postselection (discards errored runs), which doesn't scale to arbitrarily deep circuits.
• Work is partially fault-tolerant, not fully fault-tolerant.

Mentioned In

• Logical Qubit Error Correction — flagship iceberg-code demonstration
• Quantum Fault Tolerance Roadmap — trapped-ion lane on the shared 2029 target

Related Entities

• IBM Quantum — parallel program on superconducting + qLDPC