Rigetti Computing Inc. believes it has cracked the challenge of scaling quantum computer systems with an entirely new approach that’s based on a modular architecture.

The company is one of a number of startups competing in the quantum computing business, alongside more traditional technology giants such as IBM Corp. and Google LLC.

Quantum computers are powered by “qubits,” as opposed to the traditional “bits” found in classic computers. The advantage of qubits is that they can represent a 0, a 1 or something else, whereas traditional bits can only be a 0 or a 1. This makes them vastly more powerful because they can perform much more complex calculations.

Rigetti has developed its Aspen quantum chips, which are built using a technique known as “superconducting quantum computing.” The qubits are made from superconducting materials and have to be kept at temperatures of near zero. The approach is similar to the one being followed by IBM and Google.

One of Rigetti’s challenges as it looks to take on those much larger companies is that, as a startup, it has nowhere near the same amount of cash lying around to design and build its quantum processors. As a result, it has lagged behind those rivals, with its most advanced quantum chip containing just 31 qubits, compared to 60 in IBM’s most recent processor.

So Rigetti is looking to overcome that disadvantage with a modular quantum architecture, which involves piecing together smaller collections of qubits on chips that will be linked together to function as a single processor.

Rigetti said its new creation is “the world’s first multichip quantum processor” and that the approach solves key challenges it has faced in scaling toward building an entirely fault-tolerant quantum computer.

The company explained that scaling up quantum computers to a level where they can actually be useful is a big challenge. The problem is that as quantum chips get bigger, with more qubits, the likelihood of failure and lower manufacturing yields increases, making it much harder to produce high-quality hardware. The company said it has overcome this by building proprietary technology that enables it to link multiple identical dies to create a large-scale quantum chip.

“We’ve developed a fundamentally new approach to scaling quantum computers,” said Rigetti founder and Chief Executive Chad Rigetti. “Our proprietary innovations in chip design and manufacturing have unlocked what we believe is the fastest path to building the systems needed to run practical applications and error correction.”

The new approach should enable Rigetti to scale up its qubit count much more rapidly. The company said it expects to make an 80-qubit system (pictured) based on the multichip technology available on its Quantum Cloud Services platform later this year, which would be more than twice as powerful as its existing system. Rigetti’s hardware can also be accessed via the cloud on Amazon Web Services Inc.’s Amazon Braket service.

“There is a race to get from the tens of qubits that devices have today, to the thousands of qubits that future systems will require to solve real-world problems,” said Amir Safavi-Naeini, assistant professor of applied physics at Stanford. “Rigetti’s modular approach demonstrates a very promising way of approaching these scales.”

Constellation Research Inc. analyst Holger Mueller told SiliconANGLE that quantum computers are very expensive things to build, and that the winners in the budding market will be those who don’t just throw their money at creating bigger machines but also come up with smart solutions to make them scale more effectively.

“Necessity traditionally boosts creativity, and this is the case with Rigetti Computing and its modular approach, combining smaller quantum chips to create much larger and more capable ones,” he said. “This approach has conceptually worked for many computing problems in the past, but it remains to be seen how successfully it can be applied to quantum platforms.”

Image: Rigetti