Google’s “mathematical recipe” for quantum computers is not 1 month old and may already be outdated

The coding that forms the basis of Google’s recent breakthrough in error-correcting quantum computers already faces fierce competition.

A big factor preventing quantum computers from fulfilling their promise — solving seemingly intractable problems in materials science, chemistry, logistics, and many other domains — is the fact that are constantly making mistakes. And as they get bigger and gain more computing power, these errors accumulate even more.

Many researchers therefore believe that the only way to build unambiguously useful quantum computers is to let them correct your own mistakes.

It was this premise that led Google researchers at Quantum AI to look for a solution to this problem, explains .

Using the Willow quantum computing processorshowed that calculations can be corrected by grouping qubits — the basic building blocks of any quantum computer — into so-called logical qubitswhich can be increased without negatively affecting performance.

A “mathematical recipe” that the team used to group the qubits is called surface code and has long been the most advanced of quantum error correction approaches.

In 2023, researchers at IBM come up with a competitor — the QLDPC code — in which each qubit is connected to six others and the seven they monitor each other to detect errors.

This approach reduces the total number of qubits needed, the IBM team estimates that could use only 288 qubits to achieve the same level of correction of errors that the surface code provides with 4000 qubits.

In fact, the IBM researchers have also been designing their quantum computing chips in order to be suitable for the connections that the QLDPC code requires.

David Shaw, of Global Quantum Intelligence, a British business intelligence company, said at the conference that advances in the QLDPC code and similar mathematical recipes have made error correction a “hotbed of innovation”.

“Maybe someone, somewhere is working on a kind of surface code that is really fantastic, but right now there is competition to the surface code“, it says Yuval Bogerfrom quantum computing company QuEra.

Sergio Boixo of Google Quantum AI, says that “the surface code is well understood, with a well-studied theoretical framework. Offers a balance between performance and necessary connectivity of qubitswhich makes it suitable for superconducting qubits and therefore for Willow.”