×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Australian Researchers Demo Random Access Quantum Optical Memory

timothy posted more than 4 years ago | from the blacker-than-a-dingo's-kidneys dept.

Data Storage 74

nuur writes "Researchers at the Australian National University have developed a new form of optical memory that allows random access to stored optical quantum information. Pulses of light are stored on a kind of 'optical conveyor-belt' that is controlled with a magnetic field. By manipulating the magnetic field, the conveyor-belt can be moved, allowing the recall of any part of the stored optical information. The research is published in Nature." You'll probably know after reading the abstract linked whether you'd be in the market to pay for the whole thing.

cancel ×
This is a preview of your comment

No Comment Title Entered

Anonymous Coward 1 minute ago

No Comment Entered

74 comments

All I know (4, Funny)

Chuck Chunder (21021) | more than 4 years ago | (#29385555)

You'll probably know after reading the abstract linked whether you'd be in the market to pay for the whole thing.

All I know is that my head hurts.

It's great how far things have come (0)

Anonymous Coward | more than 4 years ago | (#29385757)

With Linux soon to use this we will not only be ahead on the desktop but Linux will be unmatchable as a supercomputer! Year of the penguin at last!

Yeah, well (5, Funny)

Anonymous Coward | more than 4 years ago | (#29385565)

For my storage requirements I need something more reliable than "random" access. Sheesh.

Re:Yeah, well (1)

bluelip (123578) | more than 4 years ago | (#29385609)

Hmmmm...... You run w/ no RAM?

Re:Yeah, well (0)

Anonymous Coward | more than 4 years ago | (#29385657)

Whoosh!

Re:Yeah, well (0)

Anonymous Coward | more than 4 years ago | (#29385849)

Just because it was an attempt at humor does not mean it actually succeeded

Re:Yeah, well (0)

Anonymous Coward | more than 4 years ago | (#29385939)

Just because it was an attempt at humor does not mean it actually succeeded

It did unless this is your first time on a forum.

Re:Yeah, well (0)

Anonymous Coward | more than 4 years ago | (#29386159)

GNU/Ubuntu, here comes the GNU/Ubuntu
Watch him walk this way and that way
Like a GNU/Ubuntu, like a GNU/Ubuntu

Re:Yeah, well (0)

Anonymous Coward | more than 4 years ago | (#29386025)

You manage to walk and breath at the same time with mind that can't even understand basic humor?

Re:Yeah, well (1)

CopaceticOpus (965603) | more than 4 years ago | (#29386507)

I have random access to all of your data, one bit at a time. Here's a little example to prove it (sorry if this freaks you out):

0

Re:Yeah, well (1)

Sky Cry (872584) | more than 4 years ago | (#29387123)

Bullshit! All my data consists of 1s!

Re:Yeah, well (2, Funny)

SCVirus (774240) | more than 4 years ago | (#29387631)

Ha! That was merely a social engineering trick. Now I know the contents of your data!
Now I merely need to learn the length...

Re:Yeah, well (1)

Lachlan Hunt (1021263) | more than 4 years ago | (#29388179)

Nah, it's encrypted using an algorithm that results in all 1's. You need to learn the key as well, so you know which bits need to be flipped to 0. But once you know the key, the actual data can be decrypted using the simple bitwise AND operation between the data (all 1's) and the key.

Re:Yeah, well (0)

Anonymous Coward | more than 4 years ago | (#29394771)

HEY, I had that data rot-2 protected. You'll be hearing from my lawyers.

Re:Yeah, well (1)

Fred_A (10934) | more than 4 years ago | (#29387243)

For my storage requirements I need something more reliable than "random" access. Sheesh.

Oh it's very reliable. You just don't know what your data will be until you read it.
And then it's gone.

RAM?? (5, Insightful)

bluelip (123578) | more than 4 years ago | (#29385579)

Doesn't really sound like 'RAM". Sounds more like a tape storage device. The term 'RAM' was coined to indicate any spot in memory could be accessed in generally equal time. Tapes have to rewind, move.

Re:RAM?? (1)

potatog (996901) | more than 4 years ago | (#29385753)

RAM is not about O(1) read latency. Quantum information can be read only once, so _on-demand retrieval of arbitrary quantum states of light_ may prove useful in quantum computation.

Re:RAM?? (1)

bluelip (123578) | more than 4 years ago | (#29385819)

Sounds like someone is about to drop out of CS and head towards a liberal arts degree.

Read up on what RAM was/is and get back to us. It'll do you well to improve your HS Freshman midterm exams in basic CS theory.

Re:RAM?? (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#29386117)

You know, despite acting an arrogant asshole you're actually pretty damn retarded. Grow up, douchebag.

http://hardware.slashdot.org/comments.pl?sid=1364663&cid=29385609

Of course it is not O(1)! (1)

PaulBu (473180) | more than 4 years ago | (#29386389)

It is (under physical constrains in out Universe, speed of light and such) is O(log(N)) in the best case (for N being number of addressable locations).

And "conveyor-belt" would imply O(N) access time, which, in my book, is not RAM, but more like tape or HDD (possibly flying by at the speed of light, but still linear, not logarithmic!).

But the experiment itself might be cool, everyone who have seen an optical table before should check out "A top view of the experiment" http://photonics.anu.edu.au/qoptics/ALE/Research/fiao_STB0057.html [anu.edu.au] for the view of it taken to the next level... (I've played with such a lovely mess, but only with photons confined to fibers, randomly spooled on lab bench, with random packaged RF chips (one of them mine ;-) ), waveguides, coax, good old banana plugs mixed with $1000 a piece 1mm connectors, and nice Agilent boxes around -- but tracing THIS one would make my head really hurt! :) )

At least I *looked* at the TFA! :)

Paul B.

Re:Of course it is not O(1)! (1)

camperdave (969942) | more than 4 years ago | (#29387321)

No, it would be O(1) for conventional RAM. You put the address on the address bus, toggle the control bits, and voila, the data is on the data bus. It makes no difference if the data is on the first page or the last page, or any place in between. It certainly does not depend on how big the RAM is.

Re:Of course it is not O(1)! (1)

Captain Segfault (686912) | more than 4 years ago | (#29387895)

How are you going to figure out *which* cell you're going to read from the RAM without looking at each of the O(log N) bits of the address? The decision to read from cell N depends on all O(log N) bits of N. It's not immediately obvious to me that *must* require O(log N) depth in your control circuitry, but it certainly isn't constant unless you allow unlimited fanin/fanout.

Re:Of course it is not O(1)! (1)

Elbows (208758) | more than 4 years ago | (#29387947)

In practice, memory addresses on a given architecture have a fixed size (usually 32 or 64 bits), and the hardware can look at all the address bits in parallel, thus allowing O(1) access to any location in RAM. It's the same reason that you can add two integers in constant time.

Re:Of course it is not O(1)! (1)

PaulBu (473180) | more than 4 years ago | (#29391395)

Of course O(log(N)) for *fixed* N is the same as O(1)! the dangers of O-notation is that in different contexts people can to disagree what relevant N is. Yes, you can sort N fixed-length integers in NlogN time, but what if integer length is growing?

As to memory access, one can argue that there is also O(sqrt(N)) term in it for conventional semiconductor RAM, organized as squarish matrix: one can access it only as often as it takes to charge word line (with capacitance proportional to sqrt(N), where N is number of bits).

And, of course, it is all irrelevant for algorithm analysis on a conventional off-the-shelf computer (unless you do arbitrary precision arithmetic), but how do you think people who *design* computers choose which, say, adder to put: one with linear area and linear (in bit length) operation time, or one with NlogN area and logN time?

Paul B.

Re:RAM?? (1)

Ihmhi (1206036) | more than 4 years ago | (#29386665)

If you want to be pedantic about it, all those little electron-y bits and whatnot move around in RAM too.

So I guess I have four gigs of tape drives plugged into my motherboard right now.

Cool. (5, Funny)

Nerdfest (867930) | more than 4 years ago | (#29385615)

It may, or may not, be useful.

Re:Cool. (-1, Troll)

Anonymous Coward | more than 4 years ago | (#29385639)

i learned a lot from your mother. specifically, i learned the importance of safe sex

Re:Cool. (0)

Anonymous Coward | more than 4 years ago | (#29385889)

That's what SHE said.

It's more than cool! (1)

renuk007 (638802) | more than 4 years ago | (#29385843)

In fact, it may, or may not, be useful; or it may be both useful and not-useful, or neither useful nor useless, or even a state between useful and un-useful. It may be useful to consider this further ... or maybe not.

Sorry I peeked (4, Funny)

RuBLed (995686) | more than 4 years ago | (#29385869)

It is not useful now..

Re:Sorry I peeked (0)

Anonymous Coward | more than 4 years ago | (#29386185)

In your universe, maybe

If you believe in wavefunction collapse the terrorists win!

Re:It's more than cool! (0)

Anonymous Coward | more than 4 years ago | (#29386347)

I looked. All I see is a cat, and it's not even alive...

Re:Cool. (1)

narcberry (1328009) | more than 4 years ago | (#29394823)

It is a superposition of useful and unusable data, until you read it.

Then Thors hammer slams down on the laws of nature, and amid lightning and a mad guitar riff, Murphy's Law and wave form collapse combine into always unusable data.

This is inferior dynamic quantum ram (0)

Anonymous Coward | more than 4 years ago | (#29385655)

You practically have to shovel cats into the system to maintain the state of any of the qbits.

You should wait for the flash-type qram which should be more humane on the cats with proper ducting for all the smoke.

Re:This is inferior dynamic quantum ram (2, Funny)

Anonymous Coward | more than 4 years ago | (#29385821)

You practically have to shovel cats into the system...

I used to work at a Chinese buffet, so that shouldn't pose a problem.

Re:This is inferior dynamic quantum ram (1)

mcgrew (92797) | more than 4 years ago | (#29388497)

You practically have to shovel cats into the system

Schrodinger's? I'd rather use beer [angryflower.com] than cats.

Did the researches just define a federal Highway? (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#29385767)

a Federal Highway with broken discs all over it that you can read?

Self destruction? (4, Funny)

burning-toast (925667) | more than 4 years ago | (#29385831)

Quantum... heh... does that mean if you read your memory the data is destroyed? :-D

Re:Self destruction? (1, Funny)

Anonymous Coward | more than 4 years ago | (#29385877)

Nah, what it means is you can no longer refer to it as "tranny porn", it's "a superposition of states" porn.

Re:Self destruction? (1, Funny)

Anonymous Coward | more than 4 years ago | (#29386181)

cool! so that means I can download 1 porn movie and have them all?

Re:Self destruction? (1)

L4t3r4lu5 (1216702) | more than 4 years ago | (#29387469)

No, simply that your data may or may not be there until you actually go to check it.

Sort of like using NT Backup.

Re:Self destruction? (1)

MartinSchou (1360093) | more than 4 years ago | (#29387875)

No, this is a special kind of quantum memory. The data is still there, it's only the storage mechanism that is annihilated [wikipedia.org], so you'll want to stand well clear of it.

Re:Self destruction? (0)

Anonymous Coward | more than 4 years ago | (#29387989)

You know, if you read a bog-standard DRAM chip, the data you just read is destroyed as well. And if you wait for a second or two, it's gone. That's why there is refresh circuitry to immediately write back everything you just read, and to go over the entire memory on idle cycles, reading and writing back the data at every storage location in its turn.

Not quantum addressable (4, Interesting)

harryjohnston (1118069) | more than 4 years ago | (#29386005)

Unfortunately from the description it would appear that the memory is not quantum addressable ... that is, you can't use a set of qubits as the address of which qubit to read. For a fully general-purpose quantum computer, we will probably need quantum addressable memory.

I looked at the lenses and mirrors (0)

Anonymous Coward | more than 4 years ago | (#29386147)

There are a pile of lenses and mirrors. The article made my head hurt (you really have to be into this kind of stuff to catch all of it), and then I saw the maze of lenses and mirrors (what, about 500 mirrors, about that many lenses, and about 1/4 that number of light sources, and beam splitters). My first thought was "hello grad student, I bet your collective head(s) hurt more now than mine did after reading the article. You knew what the article meant after first quick read, but got a sore head (all of you) from having to align all of that. Better you than me.

Why this could be useful: (5, Interesting)

Cordath (581672) | more than 4 years ago | (#29386163)

While light can be bounced around, absorbed and re-emitted fairly well in a classical sense, it gets tricky when you start trying to store single photons that have been intentionally "dicked with" to encode quantum information. (i.e. Quantum bits, or qubits) What this paper is talking about is one way of implementing quantum memory for successfully storing and recalling photonic qubits. (i.e. light)

Now, the computer geeks out there probably heard "qubits" and immediately thought "OooOOOooo... Quantum Computers!". Not so fast. Photonic qubits are generally too quick to decohere (even when stored in memory such as this) and difficult to interact with to be good candidates for quantum computing. It's certainly not impossible, and perhaps even probable in the long-run, but atomic qubits are currently more promising and more widely being looked at for quantum computing. What a photonic quantum memory is immediately useful for is communications. i.e. Quantum cryptography. More specifically, building quantum repeater networks.

If you know a little about computer networks, you know that signals traveling over long distances have to be boosted by repeaters every so often or loss humps your data. Optical networks are exactly the same. After a few hundred kilometers of fiber you have a lot of loss. Unfortunately, unlike classical bits, which can simply be copied, qubits cannot be reliably copied. (Google the "no cloning" theorem if you care.) The work around is a little complex to explain (it's essentially a daisy chain of entanglement swapping), but requires quantum memory to work.

The short of it is, this sort of quantum memory will allow us to build longer distance quantum encryption networks than currently exist. (Quantum crypto is currently being used by some European banks.) At first, this might allow banks in North America to jump on the Quantum bandwagon. It's hideously expensive at the moment, naturally, and probably less economical than running volkswagen's full of hard-drives with one-time-pads on them back and forth, but in principle nothing about this tech is any more expensive than the repeaters the internet currently runs on. Economy of scale should eventually kick in, and these quantum crypto networks will be pretty handy if quantum computers manage to toast public key encryption. (Authentication, of course, is another issue entirely...)

Now, I haven't had a chance to read the Nature paper yet. I've read this groups past papers though, and they really are world leaders in experimental CRIB implementation. Last I checked, they still didn't have adequate efficiency to make their tech useable (must be greater than 50% recall to be practical). Still, CRIB is one of the more promising methods out there.

Re:Why this could be useful: (3, Interesting)

Anonymous Coward | more than 4 years ago | (#29386243)

Unfortunately, unlike classical bits, which can simply be copied, qubits cannot be reliably copied. (Google the "no cloning" theorem if you care.) The work around is a little complex to explain (it's essentially a daisy chain of entanglement swapping), but requires quantum memory to work.

Correct me if I'm wrong here, but wouldn't that same work-around also allow someone to functionally tap into a quantum communications network, thereby invalidating the cryptographic utility of quantum communications?

Re:Why this could be useful: (4, Informative)

Cordath (581672) | more than 4 years ago | (#29386621)

Depends on the type of network. For plain ol' BB84 systems relying on sending single qubit states, absolutely. You wouldn't use that over a quantum repeater network though. You'd likely use one of several quantum key distribution schemes relying on shared entanglement. (e.g. Ekert 92)

Here's the principle on which quantum repeater networks will operate:

Alice (----- Entangled Photon Pair Source -----) Bell State Measurement (------ Entangled Photon Pair Source -----) Bob

What we want is for Alice and Bob to each wind up holding half of an entangled pair of photons. The two sources create two pairs of entangled photons and send the halves in opposite directions. Alice and Bob initially receive photons that have nothing to do with each other. However, when the other halves of Alice and Bob's pairs are annihilated together in the Bell State Measurement in the middle, the entanglement of the annihilated photons is swapped to Alice and Bob's photons such that they wind up being entangled together. The nice thing about this is that Alice and Bob can verify that they share entangled pairs and there's no way for anyone in the middle to fool them, provided Alice and Bob authenticate each other and there are no real-world deficiencies in their apparatus. In essence, Alice and Bob don't have to trust the man in the middle even though he's handling their photons.

To build a quantum repeater network, you just expand this out in a giant daisy chain with many many steps. Quantum memory is necessary for caching photons at each node in the chain so that you can wait for all nodes to be ready before proceeding with the bell state measurements. Caching is necessary because the probability of photons reaching each of the stations in the network simultaneously is no better than the probability of one photon going from end-to-end. i.e. Not bloody likely over long distances.


P.S. Funny aside: The first BB84 system built by Bennett and Brassard (the first quantum crypto system ever built), had some rather noisy pockel cell's controlling measurement bases such that you could tell what basis Alice was measuring in from the sound of the cell. Additionally, Alice and Bob were on the same lab bench, so an eavesdropper in between them would necessarily be inside the room. It was therefore famously joked that the first quantum crypto system was only secure if any potential eavesdropper was stone deaf! This is an example of a side-channel attack that can occur when reality doesn't quite live up to theory, and is the sort of thing people building any kind of crypto system, quantum or otherwise, have to worry about.

Re:Why this could be useful: (1)

ibsteve2u (1184603) | more than 4 years ago | (#29398633)

I wonder; as some start playing around with using quantum entanglement to create a not, do the string theorists start worrying about their jerking a knot in the universe(s?).

*ep! (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#29386277)

RRots and gets on OUTER SPACE THE and enjoy all the achievements that

Ahh... Magnetic fields... (1, Funny)

Anonymous Coward | more than 4 years ago | (#29386291)

... is there anything you CAN'T do?

Oui (0)

Anonymous Coward | more than 4 years ago | (#29386361)

Throw some quarks on the barbie aye mate? Theres a sport.

Quantum Clippy (2, Funny)

Linker3000 (626634) | more than 4 years ago | (#29387843)

Can you just imagine it...

"It looks like you want to save your last hour's edits to disk. Well, maybe they're in Quantum RAM, maybe they're not. Do you want me to have a look?"

[YES] [NO] [BOTH]

Prior art (0)

Anonymous Coward | more than 4 years ago | (#29388067)

This [wininizio.it] laptop has 2TB quantum disk.

Quantum Leap? (1)

Samah (729132) | more than 4 years ago | (#29389283)

"Damnit Al, why haven't I leaped!"
"Ziggy says you have to manipulate the magnetic field first!"

I would love to tag it but, ... (1)

Lord Byron II (671689) | more than 4 years ago | (#29391593)

I would love to tag it but, the new /. code doesn't allow Firefox to interact with the main page. For those of you using IE, I suggest you tag it with "RAQOM".

If you study in lund... (0)

Anonymous Coward | more than 4 years ago | (#29417923)

http://www.nature.com.ludwig.lub.lu.se/nature/journal/v461/n7261/full/nature08325.html
Use your STIL login and you can read the article there.

Check for New Comments
Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Sign up for Slashdot Newsletters
Create a Slashdot Account

Loading...