A new method for “entangling” photons could one day allow information to be more densely stored on CDs and other memory devices.

By entangling the photons, they share a single quantum state, which makes them behave like a single photon with a shorter wavelength and higher energy.

This overcomes the diffraction limit (light cannot be used to see or inscribe features that are smaller than half its wavelength), which limits the density of data on a CD, for example, and the size of the circuits that can be carved into microchips.

Entangling photons in groups of three would increase the CD’s capacity by a factor of nine.

Nature (vol 429, p 158/161)