Quantum computing equipment at UCL

Qubit demonstrated on conventional silicon chip

Image credit: A. Abrusci / UCL

Researchers from University College London (UCL) and Oxford University have demonstrated a single qubit on a standard transistor chip made using existing manufacturing technology, suggesting the possibility of performing quantum computing operations on chips produced in factories using conventional technology.

The basic unit in quantum information is the qubit (analogous to the classical binary bit) which can exist in binary states (represented as 0 and 1) or a superposition of these states. Quantum phenomena such as superposition could render quantum computers exponentially faster than classical computers with regards to certain problems, such as integer factorisation.

Now, UK researchers have demonstrated it may be possible to build quantum computers using industrial-grade silicon chips using existing manufacturing processes, rather than requiring the development of new manufacturing processes.

Working in a low-temperature laboratory, a team of researchers isolated and measured the state of a single electron qubit in a silicon transistor manufactured using CMOS technology: a fabrication process used to manufacture various types of chip. The spin of the electron was found to remain stable for a period of up to nine seconds.

“Every physics student learns in textbooks that electrons behave like tiny magnets with weird quantum properties, but nothing prepares you for the feeling of wonder in the lab, being able to watch this “spin” of a single electron with your own eyes: sometimes pointing up, sometimes down,” said Virginia Ciriano-Tejel, the UCL PhD candidate who led the demonstration.

The next step is to use a similar manufacturing technology to demonstrate how an array of electrons can interact to perform quantum logic operations. Quantum computers will require at least millions of qubits to perform stable, error-free calculations in the future.

“We’re hacking the process of creating qubits, so the same kind of technology that makes the chip in a smartphone can be used to build quantum computers,” said Professor John Morton, a nanotechnology expert at UCL and co-founder of Quantum Motion. “It has taken 70 years for transistor development to reach where we are today in computing and we can’t spend another 70 years trying to invent new manufacturing processes to build quantum computers.”

“We need millions of qubits and an ultra-scalable architecture for building them. Our discovery gives us a blueprint to shortcut our way to industrial scale quantum chip production.”

Quantum computers, despite having different strengths and applications to classical computers, could enable scientists to perform faster, more accurate research in areas such as drug development and climate simulation.

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