IBM quantum processor achieves highest fidelity for the longest time on record

A multi-institution study reports a new record for logical-qubit fidelity on superconducting processors using a hybrid protocol called normalizer dynamical decoupling, reaching 98.05% peak fidelity and 84.87% after 55 microseconds.

Researchers report a new record for logical-qubit fidelity on superconducting quantum processors and describe a hybrid method that reduces certain error sources. The study, published Feb. 27 in Nature Communications, involved teams from IBM, RWTH Aachen University and the startup Quantum Elements. The article mentions experiments on IBM's 127-qubit Kyiv and Marrakesh processors. The work adapts dynamical decoupling to the logical qubit layer using a code-based “normalizer” to time pulses. Reported findings: - The team combined error-suppression and error-correction into a hybrid protocol called normalizer dynamical decoupling (NDD). - The study reports a peak encoding fidelity of 98.05% and a maintained fidelity of 84.87% after 55 microseconds. - Earlier reported efforts reached peak fidelities of about 79.5% and 93.7% that fell to roughly 30% after about 27 microseconds. - The systems used are reported as prone to a type of noise called "ZZ crosstalk," which the protocol aims to suppress before logical errors form. - The authors note that applying decoupling at the logical-qubit layer allows pulses to align with the machine’s code rather than pulsing each physical qubit independently. Summary: The reported technique extends how long superconducting logical qubits can hold high-fidelity states, increasing the window for consecutive quantum operations to roughly 4,500–5,500 gates within the 55-microsecond period. Undetermined at this time.