Riverlane Ltd., a U.K. startup working to make quantum computers more reliable, today disclosed that it has closed a $75 million Series C funding round.

Growth equity firm Planet First Partners led the investment. It was joined by a half-dozen other institutional backers, including Altair Engineering Inc., a publicly traded provider of simulation software. TechCrunch cited sources as saying that Riverlane is now worth more than $400 million.

Today’s quantum computers can only perform relatively simple processing tasks. One of the main reasons such machines don’t lend themselves to more complicated calculations is that they’re prone to errors. In many cases, quantum machines can only complete a few hundred computing operations before they start making processing mistakes.

The main factor behind the technology’s reliability issues is that qubits, the basic building blocks of a quantum computer, are highly susceptible to external interference. Even a slight change in temperature or a signal from a nearby wireless device can delete the data stored within a qubit. Companies such as Microsoft Corp. are exploring ways of making qubits from materials that are less susceptible to interference, but the effort is in an early stage.

Riverlane is also tackling quantum computers’ reliability challenges, but from a different angle. The company has developed a hardware system called Deltaflow that can be attached to a quantum computer to mitigate its processing errors. According to Riverlane, the module is compatible with all the most common types of qubits that are used in today’s quantum computers.

Deltaflow comprises three main components. There’s a so-called universal interface that reads the data generated by a quantum computer’s qubits, including any errors the data may contain. This information is then loaded into a module called a decoder that detects the errors and fixes them. Deltaflow’s third component, the so-called orchestration layer, coordinates the work of its other modules.

The system has been adopted by several organizations including the Oakridge National Lab and the U.K.’s National Quantum Computing Centre. Rigetti Computing Inc,. a publicly traded quantum chip developer, is a customer as well. 

Riverlane says the current iteration of Deltaflow can facilitate 1,000 error-free quantum computing operations. The company is currently developing an upgraded version, Deltaflow 2, that will support ten times as many operations. Riverlane’s engineers expect to build the first Delta 2 system by year’s end. 

The funding round announced today will support the company’s longer-term plans for a system that can facilitate 1 million error-free quantum operations. Riverlane hopes to build that system, which will be known as Deltaflow Mega, by the end of next year at the earliest.

Photo: Riverlane