IonQ/Oxford Ionics report >99.99% two-qubit gate fidelity on trapped ions without ground-state cooling
On 2025-10-21 IonQ announced a >99.99% (four-nines) two-qubit gate fidelity result on trapped-ion hardware using Electronic Qubit Control / a 'smooth gate' technique developed by the Oxford Ionics team (now part of IonQ), surpassing the prior 99.97% record. The underlying preprint (arXiv:2510.17286, submitted 2025-10-20) reports a two-qubit gate error of 8.4(7)×10^-5 achieved without ground-state cooling, at phonon occupations up to 9.4. IonQ stated the technique is intended to underpin its 256-qubit prototype systems planned for 2026.
Crossing four-nines two-qubit fidelity is a named-metric benchmark improvement over the prior 99.97% record on a primary-verifiable preprint, the threshold at which a hardware result becomes investor-relevant per the §8 benchmark anchor.
Sub-10^-4 gate error eases the physical-to-logical-qubit overhead for fault tolerance; achieving it without ground-state cooling reduces system complexity, strengthening IonQ's engineering case for its 2026 scaling roadmap.