UCC scientists make discovery that could change quantum computing

28 Jun 2023

Lead author Joe Carroll of UCC. Image: Clare Keogh

Lead author Joe Carroll of UCC said the team have discovered a new superconductor state that physicists have been searching for for decades.

Scientists at University College Cork (UCC) have made a new discovery that could have “significant consequences” for the future of quantum computing.

Using one of the world’s most powerful quantum microscopes, researchers at the Macroscopic Quantum Matter Group laboratory discovered a spatially modulating superconducting state in a new and unusual superconductor called Uranium Ditelluride (UTe2).

Joe Carroll, lead author of the study published in Nature today (28 June), explained how the superconductor may be the key to one of quantum computing’s greatest challenges.

“Typical, classical computers use bits to store and manipulate information. Quantum computers rely on quantum bits or qubits to do the same. The problem facing existing quantum computers is that each qubit must be in a superposition with two different energies – just as Schrödinger’s cat could be called both ‘dead’ and ‘alive’.

“This quantum state is very easily destroyed by collapsing into the lowest energy state – ‘dead’ – thereby cutting off any useful computation. This places huge limits on the application of quantum computers.”

However, since the discovery of UTe2 five years ago, Carroll says there has been a huge amount of study with evidence pointing to it being a superconductor which may be used as a basis for topological quantum computing.

“In such materials there is no limit on the lifetime of the qubit during computation opening up many new ways for more stable and useful quantum computers,” he said, adding that Microsoft has already invested billions of dollars into topological quantum computing.

A new type of superconductor

Essentially, Carroll along with UCC quantum professor Séamus Davis and the rest of the team, found that some of the electron pairs passing through the superconductor form a new crystal structure embedded in the background fluid (that is, the macroscopic quantum mechanical fluid formed by pairs of electrons when moving through the superconductor).

“These types of states were first discovered by our group in 2016 and are now called Electron Pair-Density Waves. These Pair Density Waves are a new form of superconducting matter, the properties of which we are still discovering,” Carroll went on.

“What is particularly exciting for us and the wider community is that UTe2 appears to be a new type of superconductor. Physicists have been searching for a material like it for nearly 40 years. The pairs of electrons appear to have intrinsic angular momentum.

“If this is true, then what we have detected is the first Pair-Density Wave composed of these exotic pairs of electrons.”

Davis, who was recently awarded the prestigious Buckley Prize in the US, told SiliconRepublic.com recently in an interview as part of our Creating the Future series that quantum computing is “a pinnacle achievement of the human race”.

“And although many of us don’t realise it, much of our civilisation depends on our control of quantum mechanics already. It’s critically important.”

In the coming weeks, the UCC Futures – Future Quantum and Photonics research project will be launched. Davis and the Macroscopic Quantum Matter Group will play a crucial role in this initiative.

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Vish Gain is a journalist with Silicon Republic