Why quantum computers use different qubit architectures and what each approach trades for performance

Sources

IBM Heron R2 and IQM Radiance superconducting qubit fidelity data, June 2026 — Reports two-qubit gate fidelities of 99.5 percent for IBM Heron R2 and 99.91 percent for IQM Radiance on 150-plus qubit processors, showing superconducting platforms closing the gap to trapped-ion fidelity leaders.

Trapped-ion all-to-all connectivity and fidelity advantages, May 2026 — Documents trapped-ion two-qubit gate fidelities exceeding 99.99 percent and explains how shared vibrational modes provide all-to-all connectivity, contrasting with superconducting nearest-neighbor constraints and thousand-fold gate speed disadvantage.

Neutral atom fault-tolerant architecture with 448 qubits, Nature January 2026 — Demonstrates reconfigurable neutral atom arrays implementing surface codes and lattice surgery with below-threshold error suppression, leveraging atom motion for long-range connectivity unavailable to fixed superconducting grids.

Photonic quantum computing room-temperature operation and probabilistic gates — Explains photonic platforms operate at room temperature and avoid decoherence through weak photon-environment coupling, but require probabilistic fusion gates rather than deterministic entangling operations, introducing resource overhead.

Google Willow below-threshold surface code demonstration, Nature April 2026 — Reports distance-seven surface code with 0.143 percent error per cycle on 101-qubit superconducting processor, achieving below-threshold performance with real-time decoding at 1.1 microsecond cycle time.

Fusion-based photonic quantum computation with probabilistic gates, Nature February 2023 — Introduces fusion-based quantum computing model using probabilistic entangling measurements native to photonics, reporting 10.4 percent photon loss tolerance and addressing deterministic gate limitations through error correction integration.

Superconducting qubit dilution refrigerator cooling requirements, May 2026 — Details how dilution refrigerators maintain superconducting processors at twenty millikelvin using helium isotope mixing, colder than outer space, to prevent thermal photons from corrupting qubit states.

Quantum error correction threshold estimates and requirements — Explains fault-tolerance threshold typically estimated around 0.1 to 1 percent physical error rate, below which error correction can suppress logical error rates exponentially as more physical qubits are added to encode each logical qubit.

Why quantum computers use different qubit architectures and what each approach trades for performance

Terms to know first

The question

The simple model

How it works

The approaches

Superconducting circuits

Trapped ions

Neutral atoms

The frontier

What to remember

Sources