The six-beam laser-cooling arrangement named for a sticky liquid is optical molasses.
An optical molasses consists of three pairs of counter-propagating laser beams, arranged along three perpendicular axes. The beams are tuned so that atoms moving toward an opposing beam preferentially absorb photons from it. Each absorption gives the atom a momentum kick opposite its motion, creating a viscous-looking damping force.
The technique was first demonstrated experimentally in 1985 by Steven Chu and colleagues at AT&T Bell Laboratories using sodium atoms. Later experiments found temperatures below the original two-level Doppler limit, helping establish polarization-gradient or sub-Doppler cooling as an important part of the explanation.
Optical molasses slows atoms but does not, by itself, hold them at a fixed location. A magneto-optical trap adds a spatially varying magnetic field to the laser beams, supplying restoring forces as well as cooling. That distinction is the main reason optical molasses should not simply be treated as another name for an ion trap or atomic fountain.