In science fiction movies, LASER
means hot! With uses ranging from LASER guns, LASER shooting out of eyes to
burn stuff, cut through things and many other hot – and somewhat fictional- uses.
However it turned out that LASERs have a very unusual, but very remarkable
It might seem counterintuitive, but
LASERs are actually used to cool atoms down to temperatures near absolute zero!
The basic idea of LASER cooling is that when an atom absorbs and re-emits a
photon, its momentum changes, and for an ensemble of atoms, their temperature
is proportional to the variance in their velocity, so if we slow down these
atoms and lead them towards more homogeneous velocities, they will cool down.
But why Lasers?
The acronym LASER stands for:
Light Amplification by Stimulated Emission of Radiation.
A LASER is a device that mainly consists of the following components:
A mirror with a reflectivity of %100 is installed at
one end of the device.
A gas, a liquid or a solid that serves us the gain
medium and creates identical photons.
Another mirror with a reflectivity of about %98