SCIENTISTS at Glasgow University have slowed down light to the speed of sound for the first time using a technique that could find a place in the super computers of the future.
The discovery has been hailed as a possible indicator that light could be used in sophisticated quantum computers, which will eventually replace current technology.
The scientists shone a simple image of an ellipse through a ruby which was rotating at the same speed as a dentist’s drill.
As it passed through the jewel, the light beam became a million times slower but also rotated, or “dragged”, by five degrees –enough to be noticed by the naked eye. Most importantly, the image emerged unaltered from the ruby.
This proves light could be used to store information within quantum computers, which work by using atoms or photons – the smallest unit of light.
If light can be slowed down or even stopped without corrupting the information it contains, it may eventually replace the transistors used in contemporary computers.
Glasgow’s University’s technique also proves the light-borne stream of information can be directed in different directions by as much as five degrees, which could have a number of uses.
It was predicted that light could become dragged when it travels through a moving substance, such as glass, air or water, by Augustin-Jean Fresnel in 1818.
Although it has been observed in experiments during the 20th century, no researchers have managed such a dramatic effect, which can be seen with the naked eye.
Dr Sonja Franke-Arnold, lecturer in optics at Glasgow University, said: “We have solved a puzzle which has existed since the 1800s.”
She thought of the technique during a eureka moment at a conference. Dr Franke-Arnold added: “We mainly wanted to demonstrate a fundamental optical principle, but this work has possible applications too.
“Images are information and the ability to store them is an important step to the optical storage and processing of quantum information, potentially achieving what no classical computer can ever match.”
The researchers will test the accuracy of their technique by conducting further tests.
Dr Franke-Arnold added: “We will use a more complicated image, such as the university logo, and see if it can pass through the ruby intact. We are very interested in quantum computing and will be discussing our findings with other scientists.”
The experiment was conducted in partnership with Professor Robert Boyd, from the Universities of Ottowa and Rochester.
Some of the current work on quantum computing uses tiny systems, some as small as atoms, which are very difficult to work with.
It is hoped that working with light could be a simpler way of developing new computers.
Dr Simon Gay, from Glasgow University’s school of computing science, said: “This experiment is interesting because it might be easier to work with light if it has been slowed down, because it gives you longer to do something useful.
“Also, very clever things have already been done with light, which is used in fibre optic telephone systems, for instance.
“Improving anything by a factor of a million is very significant. It is likely that we will have quantum computing in some form or other and discoveries like this might allow us to improve the technology by using light rather than atoms.”
According to the laws of physics, light travels at a constant speed in a vacuum, but it has long been known that it slows down when travelling through a substance.
In the 19th century, scientists attempted a similar experiment using flowing water and found that light did slow down, but nowhere near as much as it did when travelling through the ruby.
Light travels at 671 million miles per hour in a vacuum but was slowed down to 768mph –the speed of sound – in the experiment.
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