The joint effort between Quantinuum's teams in the USA and UK and Microsoft's quantum computing division culminated in the development of four logical qubits, showcasing error rates that are 800 times lower than the corresponding physical error rates. Remarkably, the team managed to execute 14,000 independent runs of a quantum circuit without encountering any errors. Such breakthroughs are critical in hastening the journey towards universal fault-tolerant quantum computing, which has the potential to dramatically alter the timeline for addressing complex real-world challenges and transform sectors like materials science and drug discovery.

This landmark achievement is attributed to the high fidelity, scalability, and versatility of Quantinuum's 32-qubit H2 quantum processor, powered by Honeywell, in conjunction with Microsoft's advanced error correction technologies. Utilising 30 of the 32 available physical qubits on the H2, the team engineered four logical qubits, described by both companies as the "most reliable logical qubits". Furthermore, they successfully demonstrated syndrome extraction, a crucial step towards realising fault-tolerant quantum computing.

"The result announced today further cements Quantinuum's position at the forefront of universal fault tolerant quantum computing. Today’s achievement was only possible using Quantinuum’s H2 quantum computer, with its unparalleled 99.8% two-qubit gate fidelities; the 32 qubits in our QCCD architecture; and all-to-all qubit connectivity. Building on the exceptional performance of our current systems, we will continue to innovate to make universal fault tolerant quantum computing a reality sooner than previously imagined.” - Rajeeb Hazra, CEO, Quantinuum.

In the new era described by Microsoft as “Level 2 Resilient”, quantum computing is capable of dealing with the issues caused by errors, and can begin to tackle meaningful challenges, such as modelling the states of molecules and materials, simulating systems in condensed matter physics, and exploring solutions to problems across many fields. Based on Microsoft’s exacting criteria, the demonstration of multiple, entangled logical qubits, with the logical qubits outperforming the physical qubits marks a long-anticipated transition into this second phase of quantum computing.

“This is an important breakthrough for quantum computing. The collaboration between Quantinuum and Microsoft has established a crucial step forward for the industry and demonstrated a critical milestone on the path to hybrid classical-quantum supercomputing capable of transforming scientific discovery.” - Dr. Krysta Svore – Distinguished Engineer and VP of Advanced Quantum Development for Microsoft Azure Quantum.

“As leaders, we will continue to innovate more rapidly than the competition, with hardware innovations and developing applications to take advantage of the new era of truly logical qubits. We will continue to ensure that our customers are the first to benefit from these and future breakthroughs. I am excited to see how they take advantage of reliable quantum computing, to generate more powerful solutions than ever to their most challenging problems.” - Ilyas Khan, Vice-Chairman and Chief Product Officer, Quantinuum.