How is laser in treatment use as cooling?

Lasers cooling treatment:

A technique which has had recent success is laser cooling. It involves atom trapping, a process where a number of atoms are confined into a particular shaped arrangement of electric and magnetic fields. Shining exacting wavelengths of laser light at the atoms or ions slows them down, therefore cooling them. Since this process is continued, they all are not fast and have the similar energy level, forming an unusual arrangement of matter termed as a Bose-Einstein condensate.