Physicists at the US National Institute of Standards and Technology have managed to store a two-frame "short film" in cloud of gas in a demonstration of quantum memory.

The marvellously-named Quentin Glorieux and colleagues used a technique that uses pulses of light (photons) and clouds of rubidium gas. When rubidium atoms are exposed to a magnetic field, their electronic energy levels split, creating many new levels. When the field is switched off, the atoms return to their normal state. These conditions can be used to create a quantum memory device, allowing for the pulses of light (and the information coded within it) to be captured, stored and then released on demand.

The team used a method of sending pulses of light into the rubidium vapour and then switching on the magnetic field. This changes the frequency of the atoms within the gas, which in turn makes them trap the photons.

When the magnetic field is switched off, the atoms release the photons (called a photon echo) and allow the information that they were holding to be retrieved. Using this technique, researchers have been able to store entire images sent through the gas for tens of milliseconds, with an accuracy of 88 percent. It can't be stored for much longer because the atoms in the gas move too quickly.

Glorieux and team have managed to use this technique to store two images at the same time, which they have -- somewhat boldly -- referred to as a short movie. They sent images of the letters T and N into the gas and then retrieved them at different times enabling the storage of a two-frame "movie". The experiment was captured by a high speed camera.

The study -- called Temporally Multiplexed Storage of Images in a Gradient Echo Memory -- will be published in Optics Express



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