Ultra-Dense Optical Storage on One Photon

Andreaskem submitted this story about researchers being able to encode an image into a photon and to later retrieve it intact. From the article: "It's analogous to the difference between snapping a picture with a single pixel and doing it with a camera — this is like a 6-megapixel camera... You can have a tremendous amount of information in a pulse of light, but normally if you try to buffer it, you can lose much of that information... We're showing it's possible to pull out an enormous amount of information with an extremely high signal-to-noise ratio even with very low light levels."

To Clarify

[logicnazi (169418)]

The Image is NOT encoded into one photon, at least not in a way that can be extracted again. Each individual photon is in a superposition of having gone all the possible paths and the set of those possible paths is the information to be extracted but when measured each photon will only reveal a small amount of information so it is only in the aggregate (by measuring lots of photons) that the initial image can be reproduced. At least this is what the article sounds like it is saying it wasn't very clear.

In fact it is probably best to think of this without quantum mechanics at all. What they did is pretty much like figuring out the shape of an object by shooting BBs at it and looking at which ones make it past the object.

The part that is supposedly new and interesting is the way they collected the photons at the other end. It didn't seem very clear on this but apparently by catching many of the photons in their device at one time it made it much easier to decode the image in the light.

Re:To Clarify

[drerwk (695572)]

Parent is right - article is not particlely clear.
By itself a photon can be described as having, location, and energy. Thanks to Heisenberg you can only know so much about location and energy at the same time. I don't recall what property fails to commute with spin, maybe time? But the total information in a single photon is at best 3 reals for location, a real for energy, and an imaginary for spin.

Re:To Clarify

[Teresita (982888)]

"Thanks to Heisenberg you can only know so much about location and energy at the same time."

Dern that Heisenberg. And you can also thank Einstein for the fact that it takes at least one year to travel one light-year.

How long to travel a light year

[benhocking (724439)]

Actually, you can travel a light year in significantly less than a year, depending on how one defines "light year" and "year". For example, if you accelerated at 1 g towards Alpha Centauri (fun fact: 1 g is just over 1 ly/yr^2!), you would reach Alpha Centauri in about 2.25 years. Of course, looking back the original distance of 4 light years would now be shortened (thanks to that fella Lorentz [fourmilab.ch]). Bonus fact: as you pass Alpha Centauri, you will be covering 5 light years (as measured in the Earth frame of re

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[elgatozorbas (783538)]

And you can also thank Einstein for the fact that it takes at least one year to travel one light-year.

I'm a tachyon, you insensitive clod!!!

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[Beryllium Sphere(tm) (193358)]

>don't recall what property fails to commute with spin, maybe time?

Spin in the non-measured axes.

Time pairs up with energy: if you look at a really fine time scale, energy is so uncertain that there's a sea of particles (m == E / c**2).

Re:To Clarify

[mspohr (589790)]

Heisenberg might have been here.

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[nuzak (959558)]

He was definitely here. We just don't know where he went.

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[mastershake_phd (1050150)]

In fact it is probably best to think of this without quantum mechanics at all. What they did is pretty much like figuring out the shape of an object by shooting BBs at it and looking at which ones make it past the object.

You mean like a X-Ray.

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[Andreaskem (999089)]

"To produce the UR image, Howell simply shone a beam of light through a stencil with the U and R etched out. Anyone who has made shadow puppets knows how this works, but Howell turned down the light so much that a single photon was all that passed through the stencil."

The article as a whole might not be very clear, but this line says that only a single photon passed through.

Re:To Clarify

[Myrv (305480)]

They simply say one photon passes through the mask at a time. They didn't say the entire image was reconstructed using that single photon.

This sounds very similar to the double slit experiment were you send single photons through a double slit and record where they land on a screen placed behind the slits. Each photon will only light up one spot on the screen but if you collect enough samples you see a pattern start to emerge that looks like the interference pattern you would expect if light passed through both slits simultaneously. Basically, each photon which passes through the slits interfers with itself to to form the interference pattern.

In the article they are simply firing the photon through a mask with a pattern in it instead of a double slit. The photon acts as if it passed through all parts of the mask at the same time. But to reconstruct the image they would have to sample many photons passing through mask.

From what I can gather the important part of the article is that they have been able to slow down each photon in order to buffer it. So you can send 100 photons through the mask (one after another) then buffer those photons for 100 ns and then pass them on to a detector that reassembles the image from the 100 or so photons. I'm also guessing they can't slow down multiple photons at a time (at least not reliably) so the ability to serialize the photons is important as well.

Re:To Clarify

[CharlesEGrant (465919)]

rom what I can gather the important part of the article is that they have been able to slow down each photon in order to buffer it.

The original press release is very poorly writen. A better article is in the Washington Post [washingtonpost.com]. Also, the title of the actual peer-reviewed article is on Howell's publication page [rochester.edu] as "All-optical delay of images using slow light" Ryan M. Camacho, Curtis Broadbent, Irfan Ali Khan and John C. Howell, Phys. Rev. Lett (in press). As you say, the centeral acheivement is in their ability to slow down the photons. Unfortunately the actual paper doesn't yet seem to be available as the Phys Rev Letter website. I think the business of encoding an image on a single photon is a confabulation by the author of the press release.

Mod parent up.

[Animats (122034)]

I think the business of encoding an image on a single photon is a confabulation by the author of the press release.

Yeah. This is just the two-slit experiment with a material with a slow propagation velocity in the optical path. It's not new physics.

What this really means for teleportation if info

[elucido (870205)]

If it is possible to teleport a proton, and it's possible also to store information in a proton, it is possible to communicate information faster than light.

This means it's possible for us to create quantum computers which transfer information instantly, I'm not even sure we know what this means yet but discovering this is like discovering atomic technology in the 1930s.

If protons can be teleported due to non locality of the quantum, it changes everything. What we really have to consider is the fact that nu

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[enharmonix (988983)]

Slightly offtopic (ready for mod-down) but one thing I've never understood about the double-slit experiment is the result you get when only one photon is sent at a time, i.e. that the interference pattern still appears. Apparently this is a good example of a) wave-particle duality (which I understand) and b) quantum determinancy (which I don't). If someone can clarify this experiment to me it would be appreciated.

Disclaimer: My exposure to quantum physics is "A Brief History Of Time", Wikipedia and teh intarweb.

Disclaimer: Mine too. I think your question is entirely on topic, though.

No, I think the wave-particle duality is specifically the same weirdness as this particular result. The single photon still behaves like a wave (as in the dual slit experiment). The surprise was that you can actually encode and preserve information about the slit in that waveform. Multiple photons went through (not much of an experiment if they only tested it on one photon), but the article also states that it is the behavior

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[by Anonymous Coward]

Sounds like the quantum bomb [wikipedia.org] problem - detecting something by using less than a single photon.

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[logicnazi (169418)]

Yes, this was why I said it was written very confusingly.

Only one photon passed through at a time but the image was then reconstructed from MANY such photons. The advance that was made was a way to slow down/store all these photons sent individually in a way that made it easier to extract the image from them.

Mod parent up

[gvc (167165)]

I just want to add: you can only shoot one bb at the photon; doing so destroys it. So you have to decide which particular bit of information you want to retrieve, and retrieving that bit renders the rest permanently irretrievable.

Quantum computing is very fun and mind-bending, and would facilitate lots of computation that we currently think of as "impossible." Being able to do encodings such as those (mis)described in the article would be one consequence.

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[Cicero382 (913621)]

Thanks for trying to clarify - but I'm none the wiser.

I suspect that I am representative of the majority of /.ers in that I have some understanding of quantum mechanics/chronodynamics etc, but I tend to think in terms of data density s2n ratios etc.

I have many questions, but the one I would *really* like an answer to in terms I can understand is:

The article and TFA say that the info is encoded in one photon. How?

AFAIK a photon can only carry so much information - viz, energy level/frequency/duration etc. A

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[Beryllium Sphere(tm) (193358)]

Remember that Einstein was offended by quantum mechanics.

If this is working like the two-slit experiment, then each photon carries more information than you can read out from it. In the two-slit experiment, a photon or an electron makes only one spot on the detector screen but even if you feed them through one at a time the pattern that builds up at the detector is what you'd see if it went through both slits at once.

Each photon that goes by the Death Star carries a complete picture of it but can only gasp

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[HiThere (15173)]

He accepted the math, but if there *is* an interpretation of Quantum Mechanics that Einstein accepted, I haven't heard of it.

OTOH, perhaps he would have accepted the multi-worlds interpretation. I'm not quite sure of the root of his disagreement. "The loving God does not play dice" is very poetic, but a bit short in clarity.
Would he have accepted superdeterminism? I somehow doubt it, though it *is* more compatible with Newtonian philosophy than the other interpretations (that I'm aware of). The past is

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[Dunbal (464142)]

figuring out the shape of an object by shooting BBs at it and looking at which ones make it past the object.

      Most people agree that this is generally called a "shadow"...

This opens the door to quantum teleportation!

[elucido (870205)]

This means, we can in theory now communicate faster than light.

Quantum Communications PDF [google.com]

Quantum Nuclear Teleportation [google.com]

This is actually bigger news than it seems. It could influence information technology, and have the potential to create strange new weapons. Let's hope we have enough sense to use it for communications and computing.

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[Dun Malg (230075)]

posting to undo an errant "overrated" mod when I meant to hit "funny". Stupid java mod system.

Photo Storage

[Freestyling (997523)]

Does this mean I can now store my photos in a nice easy to carry cartridge or caesium gas? This is a great improvment on these clunky microSD cards I use now.

Incorrect summary

[forand (530402)]

Both the poster's summary and the news release are incorrect. You cannot encode more information than quantum numbers on any quanta, it is not possible. I believe that another poster has a plausible explanation for what is actually going on: that they measure many photons and reconstruct the information by knowing the possible paths which do the encoding of information.

A photon carries a lot of information

[by Anonymous Coward]

Any photon has a frequency (wavelength, energy, whatever). The frequency is not quantified and can assume infinite values. By generating a photon with the correct energy, I have encoded, in theory at least, a vast amount of information. Of course your ability to encode and decode very much information is limited by the available technology and the noise environment. :-)

Re:

[unchiujar (1030510)]

Not so, :) A single number can store a huge amount of information. Your hardrive is one single very long binary number. If you define a way of retrieving information you can store images as numbers (binary, hex, octal,decimal or otherwise).

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[ClosedSource (238333)]

I think the GP acknowledged that case. The problem in encoding information in a single natural entity is precision. It's the old "significant figures" issue from Chemistry 101.

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[ClosedSource (238333)]

Saying that the number of bits that can be encoded depends on the number of possible states is just another way of saying it depends on the precision.

Looks like 4 bytes per photon

[ClosedSource (238333)]

"So, our photon could easily have more than ten to the tenth states. I leave the arithmetic to you as an exercise."

That looks like about 33 bits or about 4 bytes per photon. Of course the equipment required to generate and measure frequencies with 33 bit accuracy probably requires a volume large enough to hold terabytes of information using more conventional means.

Reminds me of a short story...

[fredklein (532096)]

This reminds me of a short story (by Clarke or Asimov, I think). It's the far future, and increasingly dense data storage (the terms "notched quark" and "nudged quark" are used) means all of Humanities knowledge fits into a single file cabinet-sized drawer. All the rest of the world-wide internet-like system consists of indexes, indexes of indexes, and indexes of indexes of indexes of... well, you get the idea. One day a worker comes across an error, and forwards it to his boss. It keeps getting sent up the chain of command until a Master Troubleshooter realizes that to fix it, he needs to refer to the original datastore location. He enters the command to find the physical location of the datastore... and gets the same error.

Uhh-oh. :-)

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[zippthorne (748122)]

Is that the one where they had an entire encyclopedia encoded onto a bar of fixed length by scoring it at a precise position such that by dividing the two lengths, the rational binary number contained all of the bits of the encyclopedia?

Links to the researchers

[Beryllium Sphere(tm) (193358)]

Howell's home page [rochester.edu]
Boyd's home page [rochester.edu]

The article isn't a good match with any project listed there.

The idea of storage by slowing something down goes back to a comically ancient technology, which was converting bits to sound waves and sending them through tubes of mercury to be detected electrically milliseconds later.

Re:Links to the researchers

[Richard Kirk (535523)]

In about 1968, IBM had an optical memory where about 2 Km of optical path was folded into something the size of a filing cabinet using mirrors, and 1 bit was circulating endlessly. Optical fibres transparent enought to do this did not happen for years. This geta a brief mention in... http://www-03.ibm.com/ibm/history/history/year_196 8.html [ibm.com]

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[Coward Anonymous (110649)]

Another approach with the same underlying concept is to shine your laser at a distant object with a reflector, the moon for example. Light that comes back from the reflector is repeated. The amount of information you can then store depends on you switching speed and distance of the object while access time is dictated by the distance of the object. For the moon, worst case access time would be 2.4 seconds.
It's not very dense or fast but it is a neat idea.

SO with a few photons

[foniksonik (573572)]

You could store as delayed and compressed wave signals... an incredibly elaborate matrix of data. It would be interesting to use something other than a physical mask to create the interference in the wave... say another set of photons in the form of a laser... would this be a form of holographic storage?

For those who want to dupe their knowledge ...

[foobsr (693224)]

http://science.slashdot.org/article.pl?sid=07/01/1 9/1646212 [slashdot.org]

... where the storage device travelled at a reduced speed of light.

CC.

Holographic Storage?

[camperdave (969942)]

The setup looks like the kind of setup you'd use for holography. Split the beam, part goes to the object, part gets used as a reference.

Anyways, the researcher is delaying the arrival of the photon by 100 nanoseconds (my guess is that this is the time it takes to traverse the cesium gas chamber as compared to it not being there. He is not storing the photon in any reasonable definition of the word storage. It merely gets delayed by its passage through the gas.

Better coverage ...

[CharlesEGrant (465919)]

I suspect the original press release [rochester.edu] and the articles on Science Daily [sciencedaily.com] and PhysOrg [physorg.com] are FUBAR. I think an article in the Washington Post [rochester.edu] is probably more accurate. Unfortunately the Phys. Rev. Letter web site doesn't seem to have the actual paper publicly available yet.

As for practical applications ...

[constantnormal (512494)]

... it would seem that it might be possible to improve a lot on the image resolution of the best optical telescopes.

From the admittedly simplified diagram of the components, it would not seem to be out of the question for this notion to be included in future orbiting camera platforms, whether for scientific or spying purposes. Imagine if the Mars Orbiter had this sort of image resolution capability, or even the Hubble Space Telescope (or its replacement).

If this were true, one profound implication...

[RyanFenton (230700)]

If this information-encoding method were true (single photon carrying megabytes of information), then there would a profound implication:

Because a computer of a given mass could then theoretically be used to completely store information of a physical structure of real objects (position and properties of each atom), these systems could then completely simulate/emulate these real objects of a mass larger than the mass of the computer, even if not in realtime. That enables a large variety of applications IF it is additionally possible to acceptably scan the data of the makeup of real objects. You could theoretically have a simulation of our physical universe, without having to use the mass of the universe to make that simulation!

Major roadblocks would be the depredation of data on the light over time, and requirements of isolating the data - if the properly shielded case for a 'light hard drive' needed to be heavy enough, or the energy needed to maintain the data were enough, it could make production impractical, even if it could do what we wanted.

Very interesting research, if the data 'storage' ends up being what they think it is.

Ryan Fenton

Interesting

[elucido (870205)]

That is a very good point.
However, take into account that fact that light can be teleported too, through quantum entanglement. Combine this with quantum computers, and then you have something really scary.

The Same News Story Twice on /. In Two Days

[Pooua (265915)]

I just wondered if anyone noticed that this news story is exactly the same as the one /. posted under the heading, Slow Light = Fast Computing [slashdot.org], on January 19?

Re:Tomorrow's news

[Teresita (982888)]

"RIAA filed a suit against University of Rochester and all of its students for "Helping those damn, dirty pirates infringe on our copyrights!!"

They turned Britney Spears' "Oops I Did It Again" into a giant single number, and imprinted that number on the photon, thus making an illegal photon.

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[snitty (308387)]

Bah, it was fair use of both the song and the photon.

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[Salsaman (141471)]

Here is exhibit A, which you will note, is a single photon.

Re:Over simplification

[Dunbal (464142)]

Using just ONE photon to produce an image?

      Ahh, but what they fail to mention is that the image is of.... tadaa, the photon!

Yes but connect the dots.

[elucido (870205)]

Did they store the image on ONE photon, or did they store it on MULTIPLE photons. Also, they didn't define what they meant by 'image'. Did they mean 'image' in a sense like storing a photograph of yourself, or did they mean 'image' in the sense that it is an energy level that only codes for ONE PIXEL in an image? From the "UR" sample images, it appears that they were able to only code each individual photo so that it functions as a pixel, rather than an image. Remember, there is a difference between pixels and images.

Sometimes, I think that researchers and engineers get so excited about things that they forget what they are talking about and are so eager to proclaim their new 'discovery' to the world that they tend to over-exaggerate and/or forget what exactly they really did.

As blown out of proportion as their claim is, it is really cool that they were actually able to code photons as pixels.

If photons can encode as pixels, and we can also teleport protons, this means that not only can you store information as protons, but there is no such thing as distance anymore. It boggles the mind. This sort of technology really would change EVERYTHING. I hope it changes everything for the better, because I'm not sure humanity is ready for this. Imagine if we discovered that we could manipulate all the matter in the universe through quantum mechanisms. I mean imagine if we actually prove that the whole m

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[gregor-e (136142)]

Imagine having a photon-detector array where each cell is one square millimeter in area, while the entire detector array is, say, one square meter, giving a total of one million discrete cells. By precisely controlling the angle of one photon, one can encode a million bits on this photon by pointing it at exactly the right cell in the photon-detector array.