Storing short movie in a cloud of gas may lead to quantum memory

May 10, 2012

Storage and retrieval of two images. (a) The spatially-integrated intensity from the retrieval of the single letter T (blue), and N (red). The yellow curve shows the storage of two images, and the curves are vertically displaced for clarity. (b) The detailed timeline of the retrieved images for 7 frames. (Credit: Quentin Glorieux, Jeremy B. Clark, Alberto M. Marino, Zhifan Zhou, Paul D. Lett)

Researchers have been able to store a single image in a cloud of rubidium atoms for several years. Now they’ve gone a step further by storing two images at the same time, Technology Review Physics arXiv Blog reports.

One of the enabling technologies for a quantum Internet is the ability to store and retrieve quantum information in a reliable and repeatable way.

One way to do this involves photons and tiny clouds of rubidium gas. Rubidium atoms have an interesting property: a magnetic field causes their electronic energy levels to split, creating multiple of new frequency levels (the Zeeman effect).

Switching the field off returns the atoms to their normal state and causes them to emit the photons, allowing the information they hold to be retrieved.

That immediately suggests a way of building a quantum memory: storing an entire image, sent into the gas by placing an image mask over the beam.

The storage lasts for tens of microseconds and the image can be retrieved with accuracies approaching 90 per cent. (The storage duration is limited by the movement of the atoms in the gas which blurs the images over time.)

World’s shortest movie?

Now, National Institute of Standards and Technology researchers have stored two images, of the letter T and the letter N, in gradient echo memory (GEM) in an atomic vapor. The sequence of pictures above shows the images being released from the gas, as recorded by a high speed camera in 100-nanosecond frames.

“We have demonstrated that multiple images can be stored and retrieved at different times, allowing the storage of a short movie in an atomic memory,” the researchers say.

Until now, sequences of images have only ever been stored at the same time in solid state media, such as holographic memories. The new technique seems to have impressive potential as a quantum memory device.

Schematic of the experimental setup for image storage in a GEM (credit: Quentin Glorieux, Jeremy B. Clark, Alberto M. Marino, Zhifan Zhou, Paul D. Lett)

Ref.: Quentin Glorieux, Jeremy B. Clark, Alberto M. Marino, Zhifan Zhou, Paul D. Lett, Temporally Multiplexed Storage of Images in a Gradient Echo Memory,