Microsoft claims 'most reliable logical qubits on record'

We're entering the age of resilient quantum computing, say Microsoft and Quantiniuum

Microsoft, in collaboration with hardware company Quantinuum, has claimed a major breakthrough in quantum error correction, which it says will propel the field into a new era of reliability and scalability.

Microsoft's quantum computing roadmap, unveiled in June 2023, laid out the company's vision for achieving a dependable quantum computing system. Its latest achievement is a steptowards that goal.

"Today signifies a major achievement for the entire quantum ecosystem: Microsoft and Quantinuum demonstrated the most reliable logical qubits on record," Microsoft's Jason Zander, EVP, strategic missions and technologies, said in a blog post.

Quantum computers promise exponentially faster processing speeds for some tasks compared to conventional silicon-based computers, offering the potential to tackle scientific calculations that would otherwise be prohibitively time-consuming.

However, the inherent fragility of the fundamental unit of quantum computing, the "qubit," poses a significant challenge. Even minor disturbances can lead to data errors, rendering the computations unreliable.

To address this challenge, quantum researchers have long pursued error-correction techniques, often necessitating the use of a larger number of physical qubits to yield a smaller set of reliable and useful qubits.

In its latest experiments, using Quantinuum's ion-trap hardware in conjunction with Microsoft's qubit-virtualisation system, the company's error correction algorithm yielded around four reliable qubits from 30 physical ones. These logical qubits exhibited an error rate 800 times better than their physical counterparts, signifying a substantial leap in quantum computing reliability.

A computer equipped with a mere 100 logical qubits holds promise for solving certain classes of problems, while a quantum machine boasting 1,000 logical qubits could confer significant commercial advantages, according to Microsoft.

"We demonstrated more reliable quantum computation by performing error diagnostics and corrections on logical qubits without destroying them. This finally moves us out of the current noisy intermediate-scale quantum (NISQ) level to Level 2 resilient quantum computing," Zander said.

Merely increasing the number of physical qubits has little value without commensurate improvements in error rates: quality is more important than quantity.

Quantinuum described the breakthrough as "not just monumental for Quantinuum and Microsoft" but "a major advancement for the entire quantum ecosystem".

"It is a crucial milestone on the path to building a hybrid supercomputing system that can truly transform research and innovation across many industries for decades to come. It also further bolsters H2's title [System Model H2 is the company's quantum computer] as the highest performing quantum computer in the world," the company stated in a blog post.

Microsoft plans to make these cutting-edge logical qubits and their functionalities accessible to subscribers through its Azure Quantum Elements services in the coming months.

Looking ahead, the company is setting its sights on reaching Level 3 in its quantum computing endeavours. At this level, quantum computers should be able to tackle projects beyond the capabilities of conventional supercomputers.