Amazon Eyes New Path to Fault-Tolerant Quantum Computer

AWS Cat Bloch
Bloch sphere of the cat qubit, along with Wigner functions at four cardinal points.

Amazon Web Services (AWS) Center for Quantum Computing scientists report they have put together a plan for quantum computer that the team says manages — at least theoretically — error-correction in a new way.

The team suggests its approach could lead to quantum advantage.

The team released their findings on ArXiv, a research pre-print server. In it, they describes an architecture that combines elements of active QEC and passive or autonomous QEC. Most papers on ArXiv have not yet been peer-reviewed.

Error-correction — often referred to as fault-tolerance — is a problem that stymies quantum computing. Because quantum computers must perform their computations in extremely sensitive conditions, any environmental interference — heat, magnetic fields and even cosmic rays — could throw off the calculation. Elaborate schemes to manage those errors have been created, but scientists are still looking for hardware solutions to help avoid errors.

The researchers say their system redundantly encodes information into a protected qubit using many other physical qubits.

According to the researchers, Active quantum error correction is “an approach for reducing gate error rates by redundantly encoding information into a protected (or logical) qubit using many physical qubits.” They describe passive or autonomous error correction as an effort that “requires engineering a physical computing system that has an inherent stability against errors.”

The authors write, “We find that with around 1,000 superconducting circuit components, one could construct a fault-tolerant quantum computer that can run circuits which are intractable for classical supercomputers. Hardware with 32,000 superconducting circuit components, in turn, could simulate the Hubbard model in a regime beyond the reach of classical computing.”

Some Caveats

Don’t break out the fault-tolerant champagne just yet. The team writes in a blog post that scalability remains a hurdle to fault-tolerant quantum computers, including this approach.

“An error-corrected quantum computer will be able to execute complex quantum algorithms despite noisy hardware that is prone to errors,” they write. “The caveat, though, is that implementing quantum error correction at scale is a monumental scientific and engineering challenge, and the quantum computing field is still in the early stages of development. In particular, the resource overhead of popular approaches such as the surface code are very large, requiring hundreds to thousands of physical qubits for every encoded logical qubit.”

Matt Swayne
Matt Swayne
Matt Swayne is a contributor at The Quantum Daily. He focuses on breaking news about quantum discoveries and quantum computing. Matt enjoys working on -- and with -- startups and is currently working on a media studies master's degree, specializing in science communication.

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