The Ekert scheme uses entangled pairs of photons.

It is these entangled pairs that were used to exceed the classical wavelength limit.

Thus the entangled pairs promise twice the resolving power of ordinary photons.

They somehow use quantum "teleportation" (it involves and entangled pair of photons) to pull this off.

Also, without sending information about the partner particle, there's no way to tell if a given particle is single or half of an entangled pair.

There I can use the other half of my entangled pair to reconstruct the original quantum state.

From their Geneva location, they created entangled pairs of photons.

Second, you can't direct which state a member of the entangled pair will be in.

The wounded raptor clung to the prey's head and the other predators closed in on the entangled pair.

In any case, "weak-coherent" quantum key systems use single-photon pulses instead of entangled pairs.