Mankind is producing so much data that storing it all is becoming more difficult every day. It is expected that by 2020 about 40 zettabytes of data will be generated per year (1 ZB = 1021 bytes); in 2025, according to Seagate, 163 ZB of data has to be stored. That is an awful lot of thumb drives...

Traditional technologies like hard disks and solid state drives are quickly reaching their limits, which is why researchers and scientists are looking for new ways to store data. Optical storage is a promising avenue to explore, especially because it allows multiple bits to be stored in a single cell.

A new method being investigated by scientists for University of Adelaide (Australia) uses nanocrystals with sizes of a few hundred nanometres as storage elements. With lasers the crystals’ electronic states can be changed in a controlled way. This modifies the fluorescence properties allowing information to be stored. Because the process is reversible the nanocrystal-based memory is rewritable.

The reason that this is possible is due to samarium atoms inside the crystal that can very efficiently change between valence states Sm3+ and Sm2+. A reader quite similar to the optical pick-up of a DVD player can recover the data.

By reducing the wavelength of the laser light and super-resolution microscopy techniques the researchers think that storage capacities of petabytes (PB) per cm³ might be possible in the future (it is believed that the human brain can store about 2.5 PB).