Scientists are a step closer to creating quantum computers after making light behave like crystal.
The research team made the discovery by inventing a machine that uses quantum mechanics to make photons act like solid particles.
The breakthrough could lead to the development of exotic materials that improve computing power beyond anything that exists today.
‘It’s something that we have never seen before,’ said Andrew Houck, an associate professor of Princeton University and one of the researchers. ‘This is a new behaviour for light.’
As well as raising the possibility to create new materials, the researchers also intend to use the method to answer questions about the fundamental study of matter.
‘We are interested in exploring – and ultimately controlling and directing – the flow of energy at the atomic level,’ said Hakan Türeci, an assistant professor of electrical engineering and a member of the research team.’
The team’s findings are part of an effort find out more about atomic behaviour by creating a device that can simulate the behaviour of subatomic particles.
Such a tool could be an invaluable method for answering questions about atoms and molecules that are not answerable even with today’s most advanced computers.
In part, that is because current computers operate under the rules of classical mechanics, which is a system that describes the everyday world containing things like bowling balls and planets.
But the world of atoms and photons obeys the rules of quantum mechanics, which include a number of strange and very counterintuitive features.
One of these odd properties is called ‘entanglement’ in which multiple particles become linked and can affect each other over long distances.
The difference between the quantum and classical rules limits a standard computer’s ability to efficiently study quantum systems.
Because the computer operates under classical rules, it simply cannot grapple with many of the features of the quantum world.
To build their machine, the researchers created a structure made of superconducting materials that contains 100 billion atoms engineered to act as a single ‘artificial atom.’
They placed the artificial atom close to a superconducting wire containing photons.
By the rules of quantum mechanics, the photons on the wire inherit some of the properties of the artificial atom – in a sense linking them.
Normally photons do not interact with each other, but in this system the researchers are able to create new behaviour in which the photons begin to interact in some ways like particles.
‘We have used this blending together of the photons and the atom to artificially devise strong interactions among the photons,’ said Darius Sadri, a postdoctoral researcher and one of the authors.
‘These interactions then lead to completely new collective behaviour for light – akin to the phases of matter, like liquids and crystals, studied in condensed matter physics.’
That new behaviour could lead to a computer based on the rules of quantum mechanics that would have massive processing power.