Computer code
A breakthrough in computer science could lead to a new breed of computers which can solve knotty problems Markus Spiske/Unsplash

A technology that researchers have described as 'magic dust' could one day be turned into a computer capable of solving problems that have so far remained intractable.

Scientists from the UK and Russia demonstrated how a type of subatomic particle made up of both light and matter – known as polaritons – could help guide a new breed of computers towards the solutions for these complex problems.

Technological advancement in a huge array of fields - ranging from physics and chemistry, to biology and economics – depends on our ability to find the optimal solutions to mathematical problems – or in other words, the absolute minimum number of steps required to solve them.

This search for an optimal solution is analogous to a hiker looking for the lowest point in mountainous terrain with many valleys, trenches and drops. They may go downhill and think that they have reached the lowest point, only to find a deeper drop lies just behind the next mountain.

While this scenario is challenging for a hiker, it is a mind-bogglingly complex task for a computer to find the solution to a problems if it contains many unknowns, parameters and constraints - as is common in the modelling of economic behaviour, for example. Even the most powerful modern supercomputers struggle.

This is where the 'magic dust' polaritons come into play. To extend the hiker analogy, the 'dust' only shines at the deepest level of the terrain, becoming an easily detectable marker. Similarly, the researchers showed how the polaritons act as a kind of 'beacon' guiding a computer towards the best solution.

The new research is published in the journal Nature Materials.

"A few years ago, our purely theoretical proposal on how to do this was rejected by three scientific journals," said Natalia Berloff, first author of the study from Cambridge's Department of Applied Mathematics and Theoretical Physics and the Skolkovo Institute of Science and Technology. "One referee said, 'Who would be crazy enough to try to implement this?!' So, we had to do it ourselves, and now we've proved our proposal with experimental data."

The polaritons – which are 10,000 times lighter than electrons – are created by shining lasers at stacked layers of atoms from specific elements like arsenic and aluminium.