How to freeze a ray of light....

Light is a wave, and waves are made of movement. Imagine if you froze a wave on the ocean - you might capture the shape of the wave if you froze the water fast enough, but when you thawed it out the ice would just melt into flat water, and the wave would have been lost.

A wave is a wave is a wave. Unless its a particle, or a cat in a box, but that's another (quantum) story.

To freeze light without destroying it you need a type of crystal that can be put into a state of 'electromagnetically induced transparency', or EIT. 

That's sciencese for 'this crystal is normally opaque, but a special combination of a magnetic field and a laser shining on it will make it transparent to one colour of light.

A guy with a laser, in a military lab. This has nothing to do with the story, it just looks cool.

Which is kind of a mouthful, and this is why researchers often fall back on scienceese.

That and it makes them sound clever.

Researchers form the Georgia Institute of Technology shone coloured light through a crystal while it was in a state of EIT, then switched the EIT off. This trapped the light inside the crystal for almost a minute - an enormous length of time if you're a light beam - and then they released it.
Most importantly they were able to retrieve an image they'd encoded into the beam, demonstrating that it hadn't been damaged or distorted b the process.

So far, so what?

Well the next generation of computers are widely expected to use light instead of electricity - so a way of storing that light, and information encoded on it, takes us one step closer to them.....