From films to atoms: This new method of storing movies could also hasten the advent of a quantum internet. Image: Everett Collection/Shutterstock
Short movies can be stored in atomic vapour.
Movies have been stored on film, compact discs and as holograms, but what about room-temperature atomic vapour. Researchers from the Joint Quantum Institute at the University of Maryland, US, have succeeded in storing and replaying an atomic movie.
The film consisted of two different letters of the alphabet (N and T), which were stored in a 20-centimetre-long cell full of rubidium (Rb) atoms. The cell is just big enough to accommodate a quantum process pioneered by the Australian National University (ANU), the gradient echo memory, which stores the image over the entire range of the cell.
The image is first absorbed by the atoms at any point in the cell, depending on whether the atoms are exposed to three fields (the electrical field of the signal light, the electric field of a controlled laser pulse, and a magnetic field). When the atoms absorb the image, the control beam is turned off, the researchers reported in the study published in Optics Express.
The image to be stored, the letter N encoded by a signal laser beam and a mask, enters from the left (pink light) and enters the storage cell filled with Rb atoms. Image: NIST
The atoms not only store the images, but they can play them back on demand — by reversing the process. By flipping the magnetic field to a contrary orientation, the control beam is turned back on and the atoms eventually remit light, reconstituting the image pulse.
The researchers first stored the letter N, followed by the letter T, and played them back in quick succession. Because the images are a few microseconds apart and can be replayed, this qualifies as a feat of cinematography.
Only eight per cent of the original light was redeemed, but researchers hope that the percentage will be improved with practice. “The thing that really attracted us to this method… is that the ANU group was able to get 87 per cent recovery efficiency from it — which is, I think, the best anyone has seen in any optical system, so it holds great promise for a quantum memory,” researcher Paul Lett says.
According to Lett, one of the biggest challenges will be keeping the atoms storing the image from diffusing away. The longer the storage time, the more diffusion will occur and the result will be a fuzzy image.
Grocery barcodes may not be stored in Rb cells any time soon, but this atomic method could potentially be used to store quantum information. “If we manage to store quantum information embedded in an image or maybe in multiple images, that could really hasten the advent of a quantum network/internet,” says lead author Quentin Glorieux.
Source: The Joint Quantum Institute
