This knowledge opens up new ways of wrangling not just photons but nearly any kind of wave, which could be useful in technology that relies on information sent and stored using light.
Delaying light's journey isn't itself all that hard. Put an obstacle of atoms in their way, as happens when light makes its journey out through the surface of the Sun, and photons will take their time slipping in and out of the forest of particles. Chill those particles right down so they lose their individual identities, and light can be set into slow motion and even stopped completely as it passes through the cloud.
More recently, it's been shown that light's pathway can be affected by changing its angular momentum, effectively twisting it so it takes longer than its usual 299,792 kilometres per second to get from A to B.
A small group of physicists from the Israel Institute of Technology and the Institute for Pure and Applied Mathematics (IMPA) in Brazil have now come up with another method, showing it's theoretically possible to weave waves of light together in such a way that they stop dead in their tracks. The trick relies on tuning the light waves so they meet at what's called an exceptional point – which describes how the features of different waves match one another at a given coordinate. By toggling the set-up in such a way that the waves can gain or lose energy, the light waves can be made to coalesce and freeze, or speed up and resume their journey out the other side.
A light-stopping device based on exceptional points hasn't been built yet. But when it is, we will be able to manipulate not just light waves, but technically any kind of wave, including sound. Given that photons are quickly becoming the new electrons in information technology, we need all the tools we can find to get a firm grip on these speedy little particles.
Source for information: http://www.sciencealert.com/using-exceptional-points-coalescing-waves-stopping-light
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