Quantum industry milestone brings mass production of quantum chips closer

Quantum Motion, a UK-based quantum computing start-up led by academics from UCL and the University of Oxford, has achieved a world-record measurement of quantum devices fabricated on a silicon chip.

The company was able to place thousands of quantum dot devices, integrated alongside control electronics operating at temperatures below a tenth of a degree above absolute zero, and all made on a single silicon chip fabricated in a commercial semiconductor foundry. This lays the foundation for the mass production of quantum chips using existing silicon manufacturing processes. The results were announced at the IEEE International Conference on Electronic Circuits and Systems in Glasgow, UK on 24^e October.

Quantum Motion’s latest chip – called Bloomsbury – is a 3x3mm² device created by a Tier 1 foundry using the same mass production processes used in the manufacture of standard electronic chips. But unlike ordinary computer chips, Bloomsbury contains thousands of quantum dots into which single electrons can be loaded, one at a time, to serve as qubits. In a huge leap forward for the mass characterization of such devices, the team demonstrated how 1024 quantum dots occupying an area less than 0.1 mm² can be measured in 12 minutes, the best in the industry. All of this is achieved at temperatures of a few tens of millikelvins (-273 Celsius), which is necessary for spin qubits to operate with a minimum error rate.

Moving from the small demonstrations of today’s quantum processors to large-scale quantum computers requires overcoming several challenges. One in particular is how to address each qubit in a large array without needing a large number of on-chip input/output connections. Quantum chips must be controlled like conventional processors, which contain billions of transistors but are interfaced to a motherboard using only a few hundred input/output connections. Achieving this requires not only fabricating quantum devices using the same processes used to fabricate conventional electronics, but also designing the electronic circuits so that they can operate at the ultra-low temperatures required for qubit operation. Quantum Motion demonstrated both achievements in its Bloomsbury chip, leading to a major acceleration in the measurement and validation of silicon-based quantum chips.

“The team has created bespoke ‘quantum primitives’, our version of the transistor, the cornerstone of conventional CMOS circuits, which we can use to trap individual electrons,” said Alberto Gomez Saiz, integrated circuit (IC) manager at Quantum Motion. “Integrating these on-chip components with conventional electronics, which we designed to operate at deep cryogenic temperatures, allowed us to read thousands of quantum devices with just 9 wires entering the refrigerator. This removed a major bottleneck for scaling.

“We developed high-frequency readout techniques and software automation to measure the array of 1024 quantum dots, showing the behavior of a single electron, in 12 minutes,” said Mr. Fernando Gonzalez-Zalba, Principal Quantum Hardware Engineer at Quantum Motion. “It’s 100 times faster than other industry efforts, which can take 24 hours or more to read the equivalent number of points.”

The chips were fabricated in a commercial foundry based on Quantum Motion designs, using 300mm wafer production processes that are used for high-yield, high-volume chip manufacturing. Working closely with the foundry to achieve this impressive result is a major step on the road to realizing a scalable quantum computer.

The chip’s name refers to Quantum Motion’s original base in Bloomsbury, which worked closely with cryogenic lab facilities at UCL, before opening its own independent lab in Islington, London, at the start. of 2022.

John Morton, CTO of Quantum Motion, commented: “This result is a true interdisciplinary effort by our integrated circuit engineers and quantum physicists and accelerates the development of mass-production quantum chips. This shows the huge potential for realizing quantum processors using advanced silicon foundry processes.

Source: http://www.quantummotion.tech/