Physicists entangle 100,000 photons

Philip Ball

Adrian Cho

Entanglement, a seemingly impossible link between distant particles, is key to physicists' plans for revolutionary quantum computers and uncrackable quantum communications systems. Creating entangled pairs of light particles, or photons, is a delicate business. Now, physicists from Japan and the United Kingdom have found a way to do it by simply passing ordinary photons through a novel optical filter.

Nicolas Gisin, John Rarity, Gregor Weihs

Xing-Can Yao, Tianxiong Wang, Ping Xu +7 more

Physicists in the US and Serbia have created an entangled quantum state of nearly 3000 ultracold atoms using just one photon.

Physicists in Canada and Austria have succeeded in entangling more than two photons for the first time. Aephraim Steinberg and co-workers at the University of Toronto have entangled three photons, while Anton Zeilinger and colleagues at the University of Vienna have created a four-photon entangled state. The wavelengths of these entangled states are three and four times shorter than the original wavelengths of the photons, which means they could be used to overcome the so-called diffraction limit. Entangled photons could therefore improve the resolution of applications such as lithography and microscopy (Nature 429 161 and 158).