THE OVERLAP OF TWO PHOTONS
Physicists routinely use a movable mirror to measure the timing of laser
pulses that are only femtoseconds (10-15 seconds) long, and now they
have extended the technique to pairs of photons. A team reporting in the
18 September Physical Review Letters studied "entangled" photons, which
are created in pairs and maintain a quantum connection with their mates.
Such photon pairs may be useful for quantum computers and cryptography,
and this new technique could complement others aimed at revealing their
properties.

Kevin A. O'Donnell and Alfred B. U'Ren, Phys. Rev. Lett. 103, 123602
Link to the paper: http://link.aps.org/doi/10.1103/PhysRevLett.103.123602
COMPLETE Focus story at http://focus.aps.org/story/v24/st11