|Prototype holographic memory that uses spin waves. (Courtesy: UC Riverside)|
A new type of memory device based on the interference of spin waves has been unveiled by scientists in the US and Russia. Data are stored in the form of magnetic bits and read out simultaneously as holographic images. Because the wavelengths of the spin waves are much shorter than those of light, the storage density of the memory has the potential to be much greater than systems based on optical holograms, and could someday be used to store very large amounts of information.
Conventional holography involves splitting a beam of laser light into an illumination beam and a reference beam. The illumination beam is fired at the object of interest and the deflected light is sent to a detector (or photographic film), where it is reunited with the reference beam. The detector records the interference between the two beams and this information is then used to create a 3D image of the object. As well as being used as a security feature on credit cards and banknotes, holograms also have the potential to store and retrieve large amounts of information in a very efficient way.
However, the storage densities that can be achieved using optical holograms are limited by the relatively long wavelengths of visible light – about 500 nm. Now, Alexander Khitun and colleagues at the University of California, Riverside and the Kotel'nikov Institute of Radioengineering and Electronics in Saratov, Russia, have created a holographic memory that uses spin waves, which have much shorter wavelengths.
Physics World: Data stored in magnetic holograms