Phys. Rev. Lett. 100, 223601 (2008)

Credit: M. SHUKER ET AL.

Capture the complex patterns of photons that make up several numerals in a vapour of rubidium atoms at 52 °C, and those images will degrade as the atoms diffuse (pictured left). But Moshe Shuker of the Technion-Israel Institute of Technology and his colleagues have found a way to store such images and then regenerate the original light beam. The numbers were created by projecting a laser beam through a stencil and exciting the atoms.

Shuker's team stored images comprising sets of three parallel lines for 2, 10, 20 or 30 microseconds (pictured far right and in descending order) using a 'phase shift' technique to counteract the effect of diffusion (shown near right). The technique involves manipulating the phase of the input image, which controls the quantum phases of the atoms. The phases of the atoms that diffuse away from an image's lines are at 180° to one another, and so cancel each other out in the restored image.

Thirty microseconds is a thousand-fold increase over the previous record for delaying an image. The work has potential applications in many fields, including quantum information processing.