[Perspective] Versatile cluster entangled light

Performing a quantum computation may seem complicated, but it can be done with a specially prepared beam of light and good photodetectors. On page 434 of this issue, Schwartz et al. (1) report on a prototype device that uses semiconductor quantum dots that generate long strings of photons in an entangled cluster state of light. Cluster states (2) carry a specific sort of entanglement—that is, the way in which the properties of different photons are correlated. In two dimensions—when the enta