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:5 dimensions? (Score:5, Interesting)
Most physicists should be perfectly comfortable applying the term "dimensions" to cases other than spatial dimensions.
Once you're used to infinite-dimensional Hilbert spaces, media articles that mention "five-dimensional storage" are only infinitesimally interesting by comparison.
Does polarization really count as a dimension? (Score:2, Interesting)
Wavelength is definitely a full dimension, as it would be possible to read data at a near infinite number of specific wavelengths. Reading should be easy because you can just pass the light through a prism and check a specific angle of refraction to find the wavelength you need. Writing would be trickier, but it's an engineering problem that can be improved upon over time.
I'm not sure if I'd call polarization a dimension because there are only two angles you can work with, the angle you start with and the angle perpendicular to it. If you try to use a third angle, data from other two will mix with what you're trying to read. So I would say polarization adds another bit (allowing you to store twice as much), but not another full dimension (potentially allowing you to store orders of magnitude more).
Re:Five dimensional in the same way... (Score:3, Interesting)
A byte is a one-dimensional, eighth-order, array of bits.
Of course, bits in this context are discrete units of information only capable of providing one of two values. This method is interesting because the "bits" are capable of providing 5 pieces of unrelated, non-interfering, pieces of data. It's perfectly acceptable to refer to it as an orthogonal, five-dimensional datum, regardless of the lack of separation in space or time, and that they are not at 90 degree angles.
Re:5 dimensions? (Score:3, Interesting)
Is that so? Isn't that slightly sloppy, from a physicists point of view?
Rotation and spin are another degree of freedom (and, IRC, has been refered to as such by my physics lecturers), but physically not another dimension.
Mathematically, a Hilbert-space state vector is infinite-dimensional. But physically, it is just a function describing the state of the system in a three dimensional space over time.
My problem with using such an expression in a PopSci article is, that it is sensationalism. It relies on the common understanding of physical dimensions as (3 x space + X), implying some other dimension besides the well known spatial ones.
Re:Five dimensional in the same way... (Score:4, Interesting)
What about color? What about weight? What about temperature? What about how much Barack Obama likes it on a scale of 1-10 assuming that's defined? All of these are valid features to include in your consideration. Perhaps you only care about two of the spacial dimensions, and it's two-dimensional.
Time is not automatically a 4th dimension. I really wish that myth would disappear. It's a convenience for visualizing some forms of 4D things (eg, imagining a hypercube as a normal cube that is gradually changing size) but you can visualize it other ways as well. I prefer to think of a hypercube as a cube plus its color.
Of course, these researchers are totally exploiting that consideration in the population to get fudning. Kind of like how you always add "with implications to homeland security" to the end of proposals, or "the Reds might already have one" in the good old days.
Re:5 dimensions? (Score:3, Interesting)
"Rotation and spin are another degree of freedom (and, IRC, has been refered to as such by my physics lecturers), but physically not another dimension"
Well they kind of are, in that they can't be collapsed into a smaller number of dimensions. If you take rotation of an object, what that refers to in the lower dimensions is the different in momentum of one side of the object to the other. If you do not include that information, to be able describe the object to the same degree of detail, you'd have to include momentum details of two different points of the object (for a single axis of rotation). Collapsing it into a single dimension loses information.
I count 6 dimensions not 5 (Score:3, Interesting)
I was wondering how two polorizations of light were being counted as dimensions, as light still needs a wavelength. Looks like each wavelength can store two bits of information, two patterns (see the photo on the article page), by polorizing it at different angles. So horizontal red is one dimension, verticle red is another; they're both used seperately. Hmm... why are they calling it 5? Am I missing something?
Re:Spinning disks and lasers (Score:1, Interesting)
You are mistaken. We're talking multiple TB per disc here, at gigabit write speeds (you didn't bother reading the article, did you?). Flash competes with things like rewritable CDs/DVDs, whereas these new discs are more around the level of storage of the current $100 1TB hard drive. And no, flash can't be layered arbitrarily many layers deep, due to heat and manufacturing tech limits; but even if it could, it wouldn't get you any real benefit - price would still scale linearly with storage capacity.
Re: gold, these things aren't made of stacks of gold doubloons or something. 10 layers of nanorods, says the article. That's likely less gold than a single sheet of gold leaf. Maybe about $1 worth. For multiple TB of data.
Re:And.. (Score:3, Interesting)
Adisde from the mis-use of the word "dimension", this is not revolutionary.
Magnetic hard disks commonly get 500GB on a much smaller platter. Why is optical so much harder?