New record for quantum measurement and control 1024 quantum bits measured in 12 minutes

Quantum Motion, a British quantum computing startup led by academics from the Universities of London and Oxford, has achieved a major milestone: the ability to integrate thousands of quantum dot devices with control electronics to operate at temperatures less than a tenth of a degree above absolute zero, all on a single silicon chip manufactured in a commercial semiconductor foundry. This lays the foundation for large-scale production of quantum chips using existing silicon manufacturing processes.

The results were presented at the IEEE International Conference on Electronic Circuits and Systems in Glasgow, UK, on October 24 [1].

01New silicon quantum bit chips: removing bottlenecks to scaling

Bloomsbury chip under a microscope showing its wire connections to a printed circuit board

Quantum Motion's latest chip, Bloomsbury, is a 3x3mm2 device manufactured by a tier-one foundry using the same mass production process used in standard electronics chip manufacturing. But unlike ordinary computer chips, Bloomsbury contains thousands of quantum dots into which individual electrons can be packed, one by one, as quantum bits. In a giant leap forward in the large-scale characterization of such devices, the team has demonstrated how to measure 1024 quantum dots with an area of less than 0.1mm2 in an industry-leading 12 minutes. All of this was achieved at temperatures of a few tens of milliKelvin (about -273 degrees Celsius): this is required for spin quantum bits to operate with minimal error rates.

According to Quantum Motion, there are several challenges to overcome to move from today's small quantum processor demonstrations to a large-scale quantum computer. One of them is simply bringing together enough quantum bits, and being able to mass-produce quantum devices using existing chip manufacturing technology is one solution to that problem.

Another problem, the company says, is how to resolve each individual quantum bit in a large array without requiring a large number of connections to the quantum device. Achieving this means not only building quantum devices using the same processes used to make traditional electronics, but also designing electronic control circuits that can function at the low temperatures needed to operate the quantum bits.

02Semiconductor technology combined with quantum physics: the potential for mass production of quantum chips

"The team has created custom 'quantum primitives,' transistorized versions of traditional CMOS circuit building blocks; we can use it to capture individual electrons and integrate these (quantum dots) with our designs of traditional ones that can operate at deep cryogenic temperatures electronics on a chip, allowing us to read out thousands of quantum devices with only nine lines going into the cooler." Alberto Gomez Saiz, head of integrated circuits at Quantum Motion, said [2], "It has removed a major bottleneck to scaling."

"We developed high-frequency readout techniques and software automation in order to measure arrays of 1024 quantum dots in 12 minutes, showing single-electron behavior. This is 100 times faster than the effectiveness of other industries, which can take 24 hours or more to read the same number of dots."

Co-Chief Technology Officer John Morton hailed [3] the result of an interdisciplinary effort by semiconductor engineers and quantum physicists at Quantum Motion, which Morton said shows the potential for quantum processors by using an advanced silicon foundry process to mass produce quantum chips.

The chips were fabricated at a commercial foundry based on Quantum Motion's design using a 300 mm wafer production process for high-volume and high-volume chip manufacturing. Working closely with the foundry to achieve this result is an important milestone on the road to a scalable quantum computer.

03A milestone for general-purpose quantum computing

But the industry is still some way from seeing a general-purpose quantum system that can deliver on the promise of the technology.

When it comes to general-purpose, large-scale quantum computers, it really depends on what you mean," Cohen said. If you want to get to what's called a fault-tolerant, large-scale quantum computer, it's going to take 10 to 15 years, maybe even 20 years. And that's when we can really harvest the full potential of quantum computers, for example, the Shor algorithm, which breaks the RSA code."

Until then, there are heuristic algorithms that have the potential to give quantum computers a major advantage in the next 5-7 years, Cohen claims, but we won't know until they are tried. He likens the situation to machine learning, which is unproven technology until people build neural networks and find them useful for specific applications. "So people are building these machines to try and see if these algorithms work; there's also a lot of work that needs to be done to try to have a general-purpose quantum computer in the future, and it needs to be done starting today."

About Quantum Motion

Quantum Motion is developing a revolutionary technology platform; not just a single quantum bit, but a scalable array of quantum bits based on the ubiquitous silicon technology already used to make smartphones and computer chips. The company is developing a fault-tolerant quantum computing architecture that is compatible with CMOS processes. Fault-tolerant quantum processors will support the most powerful quantum algorithms, with the goal of solving problems that are currently intractable in fields as diverse as chemistry, medicine and artificial intelligence.

Reference links:

[1]https://2022.ieee-icecs.org/

[2]https://quantummotion.tech/quantum-industry-milestone-brings-mass-production-of-quantum-chips-closer/[3]https://www.theregister.com/2022/10/31/quantum_motion_spin_qubit/