Researchers Store Optical Data In Five Dimensions 239
Al writes "Researchers from Swinburne University of Technology in Victoria, Australia, have developed an optical material capable of storing information in five dimensions. Using three wavelengths and two polarizations of light, the Australian researchers were able to write six different patterns within the same area. The material is made up of layers of gold nanorods suspended in clear plastic that has been spun flat onto a glass substrate and multiple data patterns can be written and read within the same area in the material without interference. The team achieved a storage density of 1.1 terabytes per cubic centimeter by writing data to stacks of 10 nanorod layers."
Re:Five? (Score:4, Informative)
X, Y, Z, wavelength, polarization
Just like how a tic-tac-toe board and a chess board are both two dimensional, despite one having a lot more locations than the other, the number of distinct polarizations or wavelengths this can detect doesn't matter. It's the number of different "things" it looks at.
Re:That's freaking kewl! (Score:3, Informative)
Hard disc platters are made from glass. A cube of glass is very difficult to break, and the surface could be protected with a layer of plastic.
Re:Misuse of the word "dimension" (Score:5, Informative)
Re:5 dimensions? (Score:5, Informative)
Your example is easy to relate to, but there's a problem people should be aware of. While you can refer to the book's location using a 6-dimensional quantity, you *could* do it in 3, by giving its position in space. In a "real" n-dimensional system, you cannot reduce the system to less than n dimensions.
A good, but less-accessible example, is the state of an object in classical mechanics. The position of an object is 3-dimensional. The state, however, is 6-dimensional: your position (3D) and momentum (3D).
Re:Five dimensional in the same way... (Score:2, Informative)
Also, you got it wrong. Their "bits", as you say, are able to store SIX, not five pieces of unrelated, non-interfering, pieces of data. By using three wavelenghts and two polarization, they get to write six different patterns in the disc.
What's happening here is that the coordinates to reach those bits are five: x,y,z,wavelength, polarization. That's why someone decided to call it a 5-dimensional space. But again, each single physical storage "node" can store 6 pieces of information. That's unrelated to the 5 dimensions.
They could use 5 different wavelengths and 4 different polarizations and it would be a 5-dimensional space that can store 20 pieces of information.
Re:Misuse of the word "dimension" (Score:3, Informative)
Re:5 dimensions? (Score:4, Informative)
Ya know, reading the actual article (yes, I know) it actually looks like it is 6 dimensions not 5 anyway... as it's 3 wavelengths x 2 polorizations, not 3 wavelengths + 2 polorizations... ie, each colour is used twice, creating 6 virtual colours, ie, 6 dimensions.
Re:I count 6 dimensions not 5 (Score:5, Informative)
Hmm... why are they calling it 5? Am I missing something?
Yes - the dimension of the system is just the number of independent variables, the 3 wavelengths and the 2 polorisations.
Think about it in terms of a 1D line vs a 2D plane. In the case of the line there is the less than 0 and greater than 0 regions. When you move up to a plane there are two new greater than 0 and less than 0s (in the y plane as opposed to the x plane of the 1D line, say). So you have 4 possible combinations (or quadrants in the plane) in 2 dimensions.
Also - note that light which is circularly polarised is both vertically polarised *and* horizontally polarised, so you can have unpolarised red light; vertically polarised red light; horizontally polarised red light and vertically and horizontally polarised red light.
(Similar to: just red light; red light and blue light; red light and green light and red light blue light and green light)
Re:And.. (Score:2, Informative)
Polarization can be a dimension, but not wavelengt (Score:5, Informative)
Wavelength doesn't really count as a dimension for stroage, nor can one store an infinite amount of information by using an infinite number of frequencies. However, polarization could be considered a dimension for the purposes of storage.
The problem with anything in the frequency domain is that you cannot encode a single frequency without creating a spread which crosses multiple frequencies. This limits how short a pulse one can encode at the desired frequency and how closely one can pack discrete frequencies together to encode different data. Coupled with the noise floor the combination limits the amount of data which can be stored in the frequency domain.
for example, if you were to look at the fourier transform of a sine wave you would see a single frequency. However, if you were to look at the fourier transform of the sine wave and INCLUDE the lack of a sine wave before and after the sine wave pulse being encoded, you would see a log of bleedover into other frequencies due to the ramp-up and ramp-down times. Any change, such as going from flatline to a sine-wave, will create a lot of harmonics. Harmonics can be reduced (but not eliminated) by using an envelope to ramp-up or ramp-down the operation, but an envelope of course requires the pulse duration to be longer. So the amount of data which can be stored is limited no matter what you do.
It works a bit differently when one is working in a quantum mechanical domain... in that case it is possible to store discrete information at discrete frequencies, but you only have particular frequencies to work with, typically related to the energy level of the electrons being knocked around.
-Matt