Oulin Yu Shows Bismuth May Enable Quantum Computing Breakthrough
By Tom Kagy | 08 May, 2025

Bismuth shaved into ultra-thin flakes reveals unexpected anomalous Hall effect at room temperatures, giving it potential to revolutionize computing.

Oulin Yu, a McGill University PhD who completed his thesis defense last November, has upended material science by showing that a non-magnetic metal can display properties once associated only with magnetic metals.

Shaving bismuth into flakes of thickness of 68 nanometers and subjecting it to extreme magnetic fields, Yu and McGill colleagues found that the flakes exhibited voltage perpendicular to the flow of an applied current, a phenomenon known as anamalous Hall effect (AHE), though bismuth is a dimagnetic metal.  

Typically AHE is only observed in ferrous metals.  What's more the effect persisted at temperatures ranging from near absolute zero (15 mK) up to room temperature (300K).

This combination of properties was so surprising that it cost Yu's PhD advisor Guillaume Gervais a bottle of wine in a losing bet against Yu and colleague Frederic Boivin, according to a recent article on Science Daily.

"We expected this effect to disappear once we increased the temperature, but it stubbornly refused," Gervais said.  "We kept going to room temperature and it was still there!  I was so sure it would vanish."

This discovery makes bismuth a wonder material and a prime candidate for super-efficient new electronics with dramatically lower energy consumption.  These properties make bismuth also potentially useful in biomedical devices as it's non-toxic and biocompatible.

The team theorizes that the atomic structure of bismuth constrains electron movement in a way that mimics the behaviour of topological materials.  Topological superconductors comprise a recently discovered state of matter in which surfaces and interiors exhibit differing properties.  

These topological properties are the basis for Microsoft's recently unveiled Majorana 1 quantum processor chip.  However, the Majorana 1 chip can only operate at temperatures near absolute zero, making it far more costly and less practical to operate than a chip that exhibits stable quantum properties at room temperature.

The possibility of applying bismuth flakes to quantum computing is a tantalizing one, and is likely driving the next phase of the team's research to see whether bismuth's AHE can be converted into the quantum anomalous Hall effect (QAHE).