All That Matters

Photo by piglicker via flickr.

I don’t have much time this week and next to blog, but yesterday Science published an interesting paper by Hui Cao and colleagues at Yale that is hard to ignore. It is the ‘anti-laser’.

In short, this anti-laser does exactly the same what a laser does, just with time reversed. You can do that because the physics involved in the laser doesn’t change when you reverse the time. It is as if you play a laser backwards.

A laser requires at least two energy states that are placed between two mirrors. An electron in an upper energy state relaxes to the lower one and emits light. If the electrons are continuously pumped into the upper state, the light that bounces between the mirrors becomes increasingly intensive and at some point lasing kicks in. One of the two mirrors is semi-transparent, so the laser light can get out of the device.

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