New model that can help develop quantum computers

The study shows that quantum entanglement – a phenomenon where particles become inextricably linked – can change the behaviour of magnets in a way that classical physics cannot explain.

Magnets are part of our everyday lives, from compasses to hard discs. Materials become magnetic because each atom contains tiny ‘magnetic needles’, called spins, which collectively create a magnetic field. Traditionally, the Landau-Lifshitz-Gilbert (LLG) equation describes the motion of spins. But this classical description fails to account for the strange world of quantum mechanics.

In the new study, researchers have developed a quantum mechanical version of this equation. The new model called the quantum LLG (𝑞-LLG) equation shows that when two spins are quantum-mechanically entangled – that is, inseparably coupled – their magnetic effect can sometimes disappear altogether.

“This effect cannot be explained by classical physics, where each spin always retains its strength. We wanted to understand how quantum physics impacts the dynamics of magnetic materials, particularly how magnetism and entanglement are linked over time in a quantum mechanical world,” explains Danny Thonig.

The study confirms that the new quantum LLG (𝑞-LLG) equation can describe both the expected classical effects and completely new quantum phenomena.

In the long term, this discovery could contribute to new technologies in spintronics – a technique where the spin of electrons is used to store and process information. It could also have implications for quantum computers, where quantum entanglement is a key component.

By understanding how quantum effects affect the dynamics of magnetic materials, researchers can develop more energy-efficient memory devices and new types of hardware for the computers of the future.