Yanfei Li

Laser light is like a perfectly aligned row of soldiers on parade: all waves oscillate in the same plane. Such light is called polarized. In a new study, physicists have for the first time produced polarized gamma rays by colliding electrons with a powerful laser pulse.

A cloud of rubidium atoms falls into a trap made of light. Lasers and magnetic fields arrange it like a crystal lattice, but the cells here are not fractions of a millimeter: they are fractions of a micrometer.