Researchers use twisted graphene multilayers to unlock radiation-free quantum technology

Rare-earth compounds have attracted researchers for decades thanks to the unique quantum properties they display, which have so far remained out of reach of everyday compounds. One of the most remarkable and exotic properties of those materials is the emergence of exotic superconducting states, and particularly the superconducting states required to build future topological quantum computers. While these specific rare-earth compounds, known as heavy fermion superconductors, have been known for decades, making usable quantum technologies out of them has remained a challenge because they contain critically radioactive compounds, such as uranium and plutonium, rendering them of limited use in real-world quantum technologies.

In a recent study, researchers from Aalto University and Paul Scherrer Institute have found a way to achieve ‘heavy fermions’ in subtly modified graphene – a cheaper and safer alternative to the rare-earth compounds in which it was possible until now. The researchers showed in their paper how the quantum state known as a “heavy fermion” can be produced by combining three twisted graphene layers. A heavy fermion is a particle – in this case an electron – that behaves like it has a lot more mass than it actually does. The reason it behaves this way stems from unique quantum many-body effects that were mostly only observed in rare-earth compounds until now. This heavy fermion behavior is known to be the driving force of the phenomena required to use these materials for topological quantum computing. This new result demonstrates a new, non-radioactive way of achieving this effect using only carbon, opening up a pathway for sustainably exploiting heavy fermion physics in quantum technologies.