How to Freeze Light | Sci Guide | Martin Archer | Earth Lab
1,004Martin explains how we can freeze light inside crystals, stopping it in its tracks to perhaps one day create Superman-like information storage.
Light travels at 299,792,458 metres per second when moving through a vacuum. Nothing can go faster than this, mainly due to weight as only mass-less photons can travel that fast.
However if photons travel though a substance like water they slow down. That's why the bottom of swimming pools look closer than they are.
Researchers in Germany have recently been able to stop light moving for an entire minute at a time. An impressive feat, as in the space of a minute light would normally be able to travel the equivalent of 450 times around the Earth.
In order to trap light, researchers used a crystal, two distinct lasers and praseodymium ions. The charged particles inside the crystal turn it opaque effectively prohibiting light to enter. By firing a laser beam at the crystal, a quantum effect takes place called 'electromagnetically induced transparency' and light of a certain colour can now enter.
The second laser is then fired, of course it has the requisite colour and while it is passing through, the first laser is deactivated, the crystal turns opaque again and the light from the second laser is trapped inside.
The slowed light trapped inside the crystal is effectively no longer light, it's a spin wave. The praseodymium ions have a property known as spin due to the electrons orbiting around their nuclei and they create the wave.
However the light can be retrieved in its original state. It retains its quantum coherence giving rise to the possibility that it could be used to store information. Just imagine, HeadSqueeze videos of the future stored inside crystals then accessed at super fast-speeds. Superman's Kryptonian crystal palace awaits!
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