Tiny Holes Advance Quantum Computing

Nick writes "Worldwide, scientists are racing to develop computers that exploit the quantum mechanical properties of atoms - quantum computers. One strategy for making them involves packaging individual atoms on a chip so that laser beams can read quantum data. Scientists at Ohio State University have taken a step toward the development of quantum computers by making tiny holes that contain nothing at all. The holes - dark spots in an egg carton-shaped surface of laser light - could one day cradle atoms for quantum computing."

Comments

Great principle

[treff89]

Quantum computing is quite simply where we turn after existing silicon is exhausted. Once the basics about the random nature of quantum particles, which is extremely interesting, the meaning of computer and mechanics thereof can be redefined.

Re:Great principle

[giginger]

I, for one, am looking forward to it. Could mean so much is possible that isn't possible now. Or at least isn't worth trying because of the power.

Re:Great principle

[NetCow]

after existing silicon is exhausted
Good one.

Re:Great principle

[koreaman]

Not necessarily. We still have a long way to go before we have useful quantum computers, and they're not an improvement over silicon for everything. We may well have diamond computers or something else fundamentally similar to silicon computers before we make the leap to quantum.

Re:Great principle

[treff89]

That's supposed to be, once we understand the basics.. From what I remember of a lecture, the real issue is actually being able to control the particle itself, but once controllable, the powers are immense.. for example, it would be possible to tell if an email has been read by "simply" observing the state of the quantum particles. Extremely advanced stuff but hugely powerful for the distant future,.

Re:Great principle

[the31337z3r0]

Heh. Leap to Quantum. Don't EVER reference that show again.

Re:Great principle

[Urkki]

• they're not an improvement over silicon for everything.

Indeed, talking about quantum computers as an improvment on silicon computers is like talking about jumbo jets as an improvement over cars. Ie not an improvment at all, unless you have something very specific to do (factor a large integer or cross an ocean). And you need the simpler alternative to use the more advanced one (car to get to the airport, regular computer to feed and extract data for quantum computing).

Re:Great principle

[koreaman]

Er, I didn't even know it was a show. Did it suck really badly? If so, I am truly sorry, and give you my express written consent to beat me over the head with a rubber chicken.

Re:Great principle

[AKAImBatman]

Quantum Leap was an excellent TV show that ran through the late 80's and early 90's. The premise was that "Dr. Sam Becket" (who now plays Captain Archer on Enterprise) invented a time machine that would allow him to reach points throughout his lifetime. The problem is that he never quite got the kinks worked out of his retrieval program, and now finds himself randomly leaping from life to life. The tagline of the show was, "striving to put right what once went wrong and hoping each time that his next leap will be the leap home." (Usually then followed by us seeing him leaping into someone's life. Something utterly confusing then happens to him and he utters the words, "Oh boy".)

And now you know... the rest of the story.

Re:Great principle

[shotgunefx]

I don't get that. Wouldn't you observing the qbits change it?

Re:Great principle

[stevok]

Not exactly. Quantum computers can simulate classical computers with no problems. That's one of the tenets of quantum computation. I would love to see a 747 parallel park in Manhattan. Also, the fact that quantum computers can factor large integers efficiently necessarily implies that they can do other NP-complete problems efficiently, such as the traveling salesman problem. If we can ever get more than seven qubits to behave, we'll be amazed by the things quantum computers can do. But, alas, scientists have only implemented Shor's Algorithm for factoring integers on one number. 15. And hot damn, they got the factors right, 3 and 5. Yes, IAWAUGTOQC (I am writing an undergrad thesis on quantum computation).

Re:Great principle

[koreaman]

Thanks for the info!
Mod parent up.

Re:Great principle

[AKAImBatman]

/me takes a bow

Bonus points to anyone who can identify my ending line. :-)

Re:Great principle

[AKAImBatman]

I need to brush up on my QC theory, but if I remember correctly, quantum computers exploit "spooky action at a distance" (aka Quantum Entanglement). This allows one set of particles to perform the real calculations, while another set of particles is observed.

Re:Great principle

[SysSupport]

Paul Harvey, g'Day.

Re:Great principle

[zwilliams07]

the random nature of quantum particles

*enters 1 + 1 into the built-in calculator*
*gets 2,124,972, 421 as an answer*
*enters 1 + 1 again*
*gets 0.0012 as an answer*

Re:Great principle

[Urkki]

• Quantum computers can simulate classical computers with no problems

So, what kind of scale are we talking about here? To simulate, say, a million-transistor CPU and a megabyte of RAM, how many qubits would you need? About as many as you need transistors, or radically less?

If the answer is millions, then I think my comparison to a jumbo jet is valid, as we're probably about as far from a quantum computer simulating even a 4004 with hundreds of bytes of RAM, than we're from ubiquitous flying cars replacing jumbos ;-)

Re:Great principle

[AKAImBatman]

Whoa. A Slashdotter who actually knows who Paul Harvey is? What's this world coming to? ;-)

Re:Great principle

[stevok]

Like the article said, the issue isn't processor speed, it's algorithm time as a function of input size, i.e. logN. Factoring integers takes an exponential amount of time on classical computers. The best known classical algorithm (called GNFS) is O(exp((logN)^{1/3}(loglogN)^{2/3})), whereas Shor's algorithm can factor N in O((logN)^3) time. But, Shor takes roughly 2^N qubits to factor N. So, if we're talking about factoring a 200 digit RSA number, that's a whole crapload of qubits to control. Many orders of magnitude more than we can control now. In short, you're absolutely right about quantum computers being completely impractical until there are some huge breakthroughs in engineering and physics. This is why I love being a math major. We don't have to worry about silly things like actually building a quantum computer. We just sit around and daydream about how a quantum computer would work, then when we've got it all figured out, we blame the physicists and engineers for not building one.

Re:Great principle

[madaxe42]

Think it might be a while before we deplete the universe of Si.... could this hold up quantum computing?

Re:Great principle

[murphj]

So, what kind of scale are we talking about here? To simulate, say, a million-transistor CPU and a megabyte of RAM, how many qubits would you need? About as many as you need transistors, or radically less?

From TFA: "In principle, quantum computers would need only 10,000 qubits to outperform today's state-of-the-art computers with billions and billions of regular bits," Lafyatis said.

Re:Great principle

[XMyth]

Sad no one has answered yet....here's another hint: citrucel!

Re:Great principle

[frakir]

But, Shor takes roughly 2^N qubits to factor N

Make that log2(N) qbits. 2^N would be a bit excessive (to factor 15 they'd need 32000 qbits. They used 7 of them)

Re:Great principle

[Anonymous Coward]

Someone did answer. The mods were unkind to him, however. I hope they get their butts kicked in metamod. :-(

Re:Great principle

[QuantumFTL]

Not exactly. Quantum computers can simulate classical computers with no problems. That's one of the tenets of quantum computation.

If by "no problems" you mean "severe and most likely insurmountable quantum coherence issues". Any quantum computer big enough to simulate a modern sized classical computer will contain so many qubits as to have problems with interference from the outside world. IIRC the problem of quantum coherence is roughly exponential in the number of qubits in a system (one of the reason we don't have 1000 qubit computers sitting around). Just having enough qubits to remember my RAM would get pretty ridiculous.

The truth is that quantum computers, in the forseeable future, will likely be an orthogonal type of computing system to classical computers - a coprocessor used for certain problems with small memory requirements but large search spaces. Many of our most important computations lie in this regime, but I doubt quantum computers will outperform classical computers on most ordinary stuff (i.e. word processing, running a webserver, handling large databases) due to its seriality and memory intensive nature. (Insert quote like "640 k ought to be enough for anybody" here)

Also, the fact that quantum computers can factor large integers efficiently necessarily implies that they can do other NP-complete problems efficiently, such as the traveling salesman problem.

It implies no such thing. Traveling salesman problem is NP-complete, and while we have no solid proof that a quantum computer cannot solve an NP-complete problem in polynomial time, Shor's algorithm is also in no way any kind of proof, as integer factorization is merely NP, not fully NP-complete as you claimed.

Yes, IAWAUGTOQC (I am writing an undergrad thesis on quantum computation).

Yes, I do have a degree in physics. You may wish to check said thesis in light of errors explained above.

Re:Great principle

[Urkki]

• From TFA: "In principle, quantum computers would need only 10,000 qubits to outperform today's state-of-the-art computers with billions and billions of regular bits," Lafyatis said.

Yes, but as far as I understand, that *only* applies to problems you can solve with 10k qubits, and that's quite a limited set.

It is my understanding that, for example, doing a filtering operation on a 2 hour film consisting of 5 megapixel images, 10k qubits would not help you much. AFAIK 1 qubit is still just one "serial" bit, even though it can be infinitely many "parallel" bits. So, as far as I understand (which could be totally wrong) 10k qubits would allow you to handle about 21x21 pixel piece of a truecolor image at a time...

But I really don't know what I'm talking about here, feel free to enlighten me... ;-)

Re:Great principle

[Wandering Wombat]

And this show still had one of the greatest final episodes ever, mixing metaphysical and even religious subjects with the sci-fi technobabble of the show's premise. I miss that show so much.

Re:Great principle

[Old Telco Guy]

Also, the fact that quantum computers can factor large integers efficiently necessarily implies that they can do other NP-complete problems efficiently, such as the traveling salesman problem.

Faster, perhaps, but you chose the word efficiently and that means something different to me. What is unique about a quantum computer that would allow it to solve NP complete problems efficiently, in comparison to existing hardware?

Re:Great principle

[Dulimano]

Also, the fact that quantum computers can factor large integers efficiently necessarily implies that they can do other NP-complete problems efficiently, such as the traveling salesman problem.

IAWAUGTOQC? No way. You know nothing about the theory of quantum computation. Factoring integers is NOT an NP-complete problem. Quantum computers are NOT believed to be able to solve NP-complete problems. Moderate parent DOWN.

Re:Great principle

[poot_rootbeer]

*enters 1 + 1 into the built-in calculator*
*gets 2,124,972, 421 as an answer*
*enters 1 + 1 again*
*gets 0.0012 as an answer*

So the Pentium was a quantum computer?

Re:Great principle

[Flamsmark]

perhaps after silicon technology is exhausted? when the measurements are so small that the costs of development skyrocket, and/or moore's law ceases to apply.

Re:Great principle

[NetCow]

Of course, but I couldn't resist :)

Re:Great principle

[Noofus]

and they're not an improvement over silicon for everything

But they might if they figure out a way to make quantum breast implants... :)

Re:Great principle

[bobhagopian]

The real difference is that quantum bits ("qubits") can exist in superpositions. Take some qubit, like the spin of nucleus (this is actually a pretty popular choice). Classically, it can point up or point down in a magnetic field. We call these orientations 0 and 1; accordingly, the spin stores the exact same information as a regular bit. Here's where the quantumness comes in: the 0 and 1 states can exist on top of each other, so that a spin is in a combination of the two states. To imagine the potential utility of this superposition, consider this (somewhat artificial) example. To store the integers 0 through 7 on a classical computer, you'd need 8 sets of three bits (i.e., 000, 001, 010, 011, 100, 101, 110, 111). You can store the same set of integers on a SINGLE set of three qubits (i.e., 0/1 0/1 0/1). Why is that useful? Say you want to figure out which of those numbers plus 5 equals 10. Classically, you'd go through the possibilities one by one until you found a match. Quantum mechanically, you can do the operation, and the only state out of the superposition that survives is the 101 state. Pretty cool, huh?

Re:Great principle

[lcsjk]

Moore's law will always apply. Our ability to make things smaller soon enough just may mean that we are having trouble keeping up with it. :)

Re:Great principle

[johnnick]

But they might if they figure out a way to make quantum breast implants... :)

Would those be of indeterminate size, location or both?

And would strippers with quantum breast implants have a higher spin number?

John

Re:Great principle

[marcosdumay]

Well, integer factorization is now known to be NP, since prime is P. The proff is very easy, verify if each factor is prime (P) and verify if their product is the number you are trying to factorize (P). The fact that remains to be known is if factorization is P or not. That may be very hard, since not problem has ever been proved not beeing P.

Re:Great principle

[PenguiN42]

Make that log2(N) qbits. 2^N would be a bit excessive (to factor 15 they'd need 32000 qbits. They used 7 of them)

I thought it was around 2N qbits to factor an N-bit number.

Re:Great principle

[Flamsmark]

it ceases to apply when it is no longer possible to double the number of components on a processor. there is a minimum size of components.

Re:Great principle

[Old Telco Guy]

Indeed! So you could set up an NP complete problem, say a routing problem, as a superposition of all solution sets, and as long as you set things up so that the only state that survives is the shortest/best/whatever route, you'd be doing NP complete problems in linear time (albeit with a lot of quantum "memory"). This means you could have a chess/go machine that played a perfect game with no heuristics necessary. Telephone routing would be perfect, business routing (airlines, FAA airways, mail, whatever) would be routed with perfect efficiency, etc. Cool.

Re:Great principle

[frakir]

I thought we were talking about factoring N rather then N-bit number...

Re:Great principle

[PenguiN42]

Actually it's more like:

*enters 1 + 1 into the built-in calculator*
*gets 2 as an answer*
*enters 1 + 1 into the built-in calculator*
*gets 2 as an answer*
*enters 1 + 1 into the built-in calculator*
*gets 2,124,972, 421 as an answer*
*enters 1 + 1 into the built-in calculator*
*gets 2 as an answer*

hmm. the answer's probably 2!

Re:Great principle

[tbo]

Yes, I do have a degree in physics. You may wish to check said thesis in light of errors explained above.

And I'm doing a Ph.D in physics on quantum computing. Sorry to be a prick about it, but you were a bit rough on the undergrad who posted above, and what goes around comes around. As long as that guy isn't doing his research on slashdot, he'll probably be OK..

If by "no problems" you mean "severe and most likely insurmountable quantum coherence issues". Any quantum computer big enough to simulate a modern sized classical computer will contain so many qubits as to have problems with interference from the outside world. IIRC the problem of quantum coherence is roughly exponential in the number of qubits in a system

No, the problem is not exponential in nature. It has been shown that if the error rates for storage, gates, etc. can be brought below certain thresholds (typically 10^-3 to 10^-6), then arbitrarily long computations can be performed. There are many papers on the subject, but here is one.

The only way in which decoherence could pose an insurmountable problem is if there is fundamentally new physics that plays a role in the regime between "quantum" and "classical". Nobel Laureate Tony Leggett has talked (in a recent issue of Science, and at the 2005 Gordon Research Conference) about how we might find such new laws of physics if they exist, or otherwise rule out their existence.

It implies no such thing.

You are correct. In the early days of the field, I think there was a little bit of confusion about whether quantum computers could do NP-complete, but it has long since been sorted out.

I recently attended a talk by Ike Chuang about general issues in the field. Chuang feels that quantum simulation and quantum communication will be the important applications, although he emphasized communication. I think quantum simulation is way, WAY underappreciated. Not only is it going to revolutionize protein folding, drug design, and other biomed applications, I have a hunch it may prove to be a prerequisite for advanced nanotech.

The article is not particularly good. The supposed problems that optical lattices will have in addressing qubits in the interior of a 3-D lattice are "solved" by using what is essentially a 2-D lattice on a chip. The same can easily be done with optical lattices.

Of course, addressing atoms inside a lattice of moderate size can be done using a high numerical aperature lens to focus an addressing beam onto a single atom. The addressing beam produces an AC Stark Shift of the appropriate hyperfine sublevels of the atom (in the case of Cesium-133 qubits, it shifts each of the mF sublevels of the F=3 and F=4 states), with the exact shift being different for different sublevels. This allows transitions in that particular atom to be driven by a microwave pulse which is detuned from all the other atoms in the lattice. Just how well can we address one atom while not disturbing atoms in adjacent planes? I'll know in a week or two. I'm currently simulating one and two qubit gates in this exact scheme. The actual experiment is also under construction, at Penn State.

Anyone interested in a distributed computing project to develop quantum computers? I could use help from developers, and later, also regular user input.

Re:Great principle

[Gate-c]

I am the one who actually made this animation for OSU research communications last week! The main story was posted at OSU with the full movies, not just screen shots http://researchnews.osu.edu/archive/eggcarton.htm

Re:Great principle

[sootman]

"Yes, IAWAUGTOQC (I am writing an undergrad thesis on quantum computation)."

You don't have to spell it out. We're all familiar with that acronym.

Re:Great principle

[flumps]

who sez we cant use strings? or something smaller?

Re:Great principle

[Flamsmark]

we can. that would be the point at which we exhaust silicone technology. see?

Re:Great principle

[Engie_Viral]

Actually, there is at least one place that we can go after we hit the wall with silicon.

Diamond (which is simply carbon in a specific configuration) has better thermaldynamic properties than silicone (which is the main limiting factor in processors today) and, from memory, is a better semiconductor.

There is much research going on to create artificial diamonds to reduce the costs associated with these so called rare and precious gems.

So basically, processors as we know them (well, almost) may be with us for a while yet, just made from a different substance.

- Engie the Techie

Disclamer: I took most of this information from a magazine article about a year back and I am working purely from memory. Also, this is NOT FACT, this is mostly MY OPINION, which is neither right or wrong nor better or worse than anyone else's opinion - it is just my opinion.

Just in time for Lonhorn!!!

[Anonymous Coward]

Will it run Longhorn?

Re:Just in time for Lonhorn!!!

[ZeroExistenZ]

If you get a quantum 3D-accelerated graphicscard.

Re:Just in time for Lonhorn!!!

[Anonymous Coward]

Probably or probably not. 50/50 either way.

Re:Just in time for Lonhorn!!!

[kpwoodr]

yes, but when it "freezes up" all particle motion will cease and your processor will collapse on itself, and take your computer and your license agreement with it. Didn't you read the EULA!

Re:Just in time for Lonhorn!!!

[NinjaFarmer]

So it will run Duke Nukem Forever then?

Re:Just in time for Lonhorn!!!

[JohnFluxx]

From the linked wikipedia page:

'According to kinetic theory there would be no movement of individual particles at absolute zero, and thus any material at this temperature would be solid. This has been proven false and it's better to describe absolute zero as the temperature where no further energy may be extracted'.

Particle motion wouldn't cease because then it would be possible to know the position and velocity at the same time - impossible with quantum mechanics.

Baby Steps

[nametaken]

I realize all new technology comes in baby steps, but its somehow disappointing to hear that they "have taken a step toward the development of quantum computers" by making one little piece.

With all the talk of quantum computers on /., one would have thought they were so much closer. :(

Re:Baby Steps

[TeatimeofSoul]

It's a step towards this particular kind of quantum computers, but there are other kinds. In fact, using NMR-technology, quantum computers have already been "made".

I say "made" since there's no actual construction needed; you just take a phial of a suitable liquid, put it in an NMR-machine and start using it. Last time I checked, which was 2-3 years ago, they'd managed to factor 15 (into 5 and 3).

This technology is unlikely to evolve into anything more powerful than existing computers, since the 'cpu' of the computer is a molecule, within which the bonds all have to be of sufficiently different strength. Also, the number of usable bits increases less than linearly with the number of atoms. More bits also means weaker signal for a given strength of the static magnetic field.

Re:Baby Steps

[el_monkeyo]

If anyone had made a working quantum computer, I'd seriously doubt they'd be in a rush to tell anyone.

Think of all the "secure" data they could harvest, and governments they could undermine.

Definitions?

[Rinzai]

"...making tiny holes that contain nothing at all."

Well, yes, that rather is the definition of "hole," isn't it? Having nothing in them is what distinguishes them from the rest of the surroundings.

Re:Definitions?

[AviLazar]

I have a hole, I place a golf ball in it - I still have a hole. It just happens to have a golf ball. The difference is one is an empty hole, the other is not.

Re:Definitions?

[EvilTwinSkippy]

Thirty spokes share the wheel's hub;
It is the center hole that makes it useful.
Shape clay into a vessel;
It is the space within that makes it useful.
Cut doors and windows for a room;
It is the holes which make it useful.
Therefore profit comes from what is there;
Usefulness from what is not there.

--Lao Tsu, The Tao Te Ching, Chapter 10

Re:Definitions?

[dillon_rinker]

By your reasoning, every cubic millimeter of every solid object is a hole that just happens to be filled.

Re:Definitions?

[AviLazar]

No that is not my reasoning at all. I said, I have a hole, I place an object in the hole, I still have a hole; it just happens to be a hole with an object in it. As for, if the hole is filled up is it still a hole, that depends on your definition of a hole.

Wow

[Anonymous Coward]

Scientists at Ohio State University have taken a step toward the development of quantum computers by making tiny holes that contain nothing at all.

Now I know people often criticise Slashdot for having summaries that contain obscure terms without explaining them, but I think it's going a little overboard to explain what a hole is :)

Re:Wow

[Vo0k]

Actually, most of holes on Earth are full on air. Even void isn't quite empty. If you have a couple of atoms forming a particle, the space between them isn't quite empty either - they partially overlap, the uncertainity principle says they "partially are" there. The idea is about making small holes with REAL void - no particles, no photons, no "with a little probability, there" electrons, just total null. Not quite easy. I, for one, can't quite imagine how are they going to stop neutrinos from entering that space...

Re:Wow

[goranb]

I, for one, can't quite imagine how are they going to stop neutrinos from entering that space

If that's all you can't imagine, you're way ahead of me... :)

Re:Wow

[Strange Ranger]

I, for one, can't quite imagine how are they going to stop neutrinos from entering that space...

Simple. They'll just repolarize the quantum invariance field and then bombard it with a tachyon pulse. This creates a standing wave of Heisenberg Flux, which is the only way to be certain the hole is empty.

Re:Wow

[Log from Blammo]

First, they will institute a massive neutrino literacy program. Then, they will post tiny signs reading "Restricted Area. No Unauthorized Leptons."

Re:Wow

[Deanalator]

I, for one, can't quite imagine how are they going to stop neutrinos from entering that space...

First off, photons need to be able to get in or there really is no point :-) Also with quantum computing, decoherence and stray particles really arent as much of a problem as they seem.

Sure, in classical computing, one strange bit flip or whatever will mess up your entire data set. Quantum computers really are for single shot calculations though. If you build a quantum computer that is going to factor a large number, but it only works a millionth of the time, it really isnt a problem to just run it a million times. You still get the answer far faster than you would on a classical computer.

Re:Wow

[madaxe42]

Ah, yes, you're right, I understand entirely. Thankyou. Just bear with me while I go re-arrange the universe to correspond with what you just said.

Re:Wow

[wgaryhas]

When did you graduate from Starfleet Acadamy?

Re:Wow

[madaxe42]

You can actually guarantee that it will be empty, by creating wave functions that overlap in such a fashion that the probability of a particle being in that space is, in fact, 0, or, by creating wavefunctions which when combined state that the probability of there not being something in that location is infinite. Picture two asymptotic curves joining at a vertical axis, mirrored.

There are a lot of extremely odd quantum effects which aren't physically possible, in any classical or comprehensible universe, however do happen. For instance, it's possible to create a negative temperature. Not negative, as in minus 22 farenheit, but negative, as in below absolute zero!

This happens when you rapidly invert the polarity of a magnetic field in which is contained a bose-einstein condensate - in the time that it takes for the condensate to re-align it's spin, it has a rapid change from a negative temperature to a positive temperature once more. The energy of a negative temperature is, actually, greater than that of an infinite positive temperature!

Anyway, enough quantum rambling. If you don't believe me, look here.

Re:Wow

[buckthorn]

... and this reply almost guarantees the parent gets a '5'.

Of course, I can't wait to see what reversing the phase inducers to create a low-level graviton well will do to the plasma injector. That stuff is so hard to clean up, though, so maybe I'd best wait until this technology stuff advances a little more. "Um, Ensign! Yes, that plasma there needs to be cleaned up, there's a mop and bucket in the corner, take care of it won't you, there's a good lad."

Re:Wow

[commodoresloat]

They're going to need a Mac to do that.

Re:Wow

[CoffeeJedi]

damn, you beat me to it :(

Re:Wow

[mikael]

I, for one, can't quite imagine how are they going to stop neutrinos from entering that space...

Just make sure all the cracks are covered by duct tape - lots and lots of it.

Re:Wow

[demondawn]

I'm actually more concerned about the creation of virtual pairs myself...

Re:Wow

[Vo0k]

Well, you can place nearby particles in such a way (technical difficulties aside), but what do you do about further ones? A near-zero-speed particle is almost everywhere, so how can you stop an electron over Jupiter from "existing inside" your hole?

Re:Wow

[madaxe42]

By placing nearby particles in a specific enough configuration you can produce a volume where the probability of anything being there is near as damnit zero - which coveres everything, everywhere - an electron over jupiter has an extremely low probability of tunneling to anywhere near our hole (although it does, in some small way, exist there), but it's existence there is so infintesimal it can be called zero.

So the data...

[Anonymous Coward]

...will be read by sharks with friggin lasers on their heads?

Mind Boggling

[CleverNickedName]

Scientists ... making tiny holes that contain nothing at all.

So these boffins have developed "nothing", but one day, in the far future, this nothing could be filled with something important.
Wow. What an age we live in.

Re:Mind Boggling

[paisley]

We've finally achieved Tao of Physics computing!

Why is the jar useful? Because it contains emptiness.

obligatory Simpsons quote:

[TheAxeMaster]

They're speed holes, they make the computer go faster....

Best part of quantum computing

[bigtallmofo]

The thing I'm really looking forward to on Slashdot 2015 are all the posts:

"Why would anyone need that much power? I remember 9 years ago when we only had 10 qubits to work with! Quantum programmers sure are spoiled and lazy today."

Re:Best part of quantum computing

[TerminaMorte]

In all fairness, you'll probally need that in order for KDE/Gnome to be usable.

Zing!

Re:Best part of quantum computing

[Craig_P92669]

But they still will only need 640k of RAM.

Re:Best part of quantum computing

[EvilTwinSkippy]

Ingrates. Back in my day I had 128 kilobits to work with, and I was privileged. Most of my friends only had 64. We had to write our own games, and we had to save them on Floppy disks! We didn't have hard drives. Hell, we didn't even have mice. We worked with our bare hands on keyboards, and by gum we were grateful.

Re:Best part of quantum computing

[RebelWithoutAClue]

You didnt . Do you plan on staying in Old Fart mode ?

Re:Best part of quantum computing

[RebelWithoutAClue]

that was meant to be

How many were there?

[sharkey]

And how many would it take to fill the Albert Hall?

Re:How many were there?

[meringuoid]

And how many would it take to fill the Albert Hall?

Four thousand.

I was never quite clear on how the holes from Blackburn, Lancs. could possibly fill the Albert Hall. I mean, they're holes - defined as being something not there. How can they fill anything?

Then I discovered marijuana, and understood :-)

Real source of technology

[Anonymous Coward]

What they didnt tell you is that the discovery of the holes stems from research into quantum alcohol fast-queuing, aka the first atomic beer-bong.

Oh come on, it is *ohio state*

Magic Red Smoke

[Analogy Man]

Everyone knows current computers and consumer electronics work using magic blue smoke. If the smoke escapes your device no longer works. Overclockers are very clumsy about letting out the blue smoke and sell their processors (depleted of magic) on e-bay under dubious accounts.

Quantum computers will use red smoke (the Rubium cloud). Will we call the hobbiests that push the limits of these machines Quark shakers?

Comment removed

[account_deleted]

Comment removed based on user account deletion

Optical Lattice

[Anonymous Coward]

It's just an optical lattice experiment of the kind which have been conducted for about 10 years. The claimed new twist is in using a single layer of atoms and not producing the lattice per se.

If Schroedinger is anything to go by. . .

[oneandoneis2]

. . . won't quantum computers mean an end to binary?

In the old days, a cat in a box was either alive or dead - one or zero, you might say. Nice and easy.

But when it gets quantum? How the hell is a simple machine going to cope when it asks "Is it one or zero?" and gets told "Both"

"We've had to replace 'if' and 'and' with 'maybe' and 'probably'. And 'not' has become obsolete."

Re:If Schroedinger is anything to go by. . .

[Hinhule]

It would be both, until the computer asks "is it one or zero" then it returns one or zero. The return value would never be both.

Re:If Schroedinger is anything to go by. . .

[x4A6D74]

The computer does not ask "is it one or zero" and get told "both."

Going back to the same metaphor you began to use, the principle that the Schroedinger's Cat Experiment is suppposed to illustrate is not the concept of superposition (that the cat is both alive and dead whilst in its quantum state in the box) but the concept of decoherence of the quantum state under observation.

It's currently a postulate of quantum mechanics (i.e. everyone observes this phenomenon but nobody can explain it) that observation of a quantum state in a superposition (say, a "qubit" -- perhaps an electron spinning up for 0 and down for 1) will have one of the two values, with certain probability. Once read, the state loses that superposition and remains in the observed state (Recall: in the SCE, the cat stays alive or dead once you open the box).

If you don't want to measure your qubits, and thus maintain their superpositions, entanglements, etc., that's fine ... of course, you can't get any information out of them. If you've properly designed your quantum machine, you may have a guess as to what the possible states are; you may even know the probability of each one.

As soon as you ask to see a qubit, however, it becomes a classical bit and stays one. That's the downside to all this quantum stuff.

Quantum computers also do not mean an end to binary -- currently, since humans have, and are trained to use, primarily classical faculties, quantum research is aimed at extending classical computation. So we typically discuss a "qubit" which may be 0, 1, or some combination thereof (specifically residing in the field C x C). But, if we ever want to interface a quantum computer with a classical instrument (for example, some sort of I/O device, or a classical computer, or a human) then we will unavoidably devolve back to binary.

For more information, I recommend Nielsen & Chuang's book on Quantum Computation and Quantum Information (I think; I don't have it in front of me right now).

Disclaimer: I am not a quantum mechanic. I am, however, an junior finishing up my degrees in mathematics and computer science so that I can go on in a year to work on a PhD in quantum computation. --0x4a6d74

Re:If Schroedinger is anything to go by. . .

[ciroknight]

A better explaination would be, "Is it a one or a zero?" "Depends on your perspective."

Quantum computing, as I understand it (IANAQCS/P) works off the principal of super position; the ability for a bit to represent multiple bits, simply by the spin of the electron, or some other random thing that I wouldn't know how to explain.

If you defined a zero as a square, and a one as a circle, then a quantum bit would be a cylinder; from one perspective you see the square, yet turn it on its side and you see its other property. But since you have other posibilities (cubes and spheres in this system), the "third dimension" persay has to be explicitly asked for by the requesting computer.

So it's able to perform a massive amount of calculations based on a little bit of data, and store it as one neat little package at the end (either the cube, the sphere, or the cylinder). When someone comes along to ask, "was the answer a zero or a one" then, the only way to answer is "depends on the perspective".

Re:If Schroedinger is anything to go by. . .

[Deanalator]

I like to think of quantum computers as binary on the outside, analog on the inside. You can only read and write in binary, but the operators in the middle can be real valued (complex valued even).

Nielson and Chuang's book is neat (I have it sitting on my floor 3 feet from me ATM). It's mainly written for the physicist to learn quantum circuits and algorithms. It takes a year to read, but by the time you are done, you should be able to read and understand most of the papers in the field.

A much lighter book on the subject is "Explortions in Quantum Computing" by Williams and Clearwater. It gives a basic overview without much assumed knowledge.

Also "Problems & Solutions in Quantum Computing & Quantum Information" by Willi-Hans Steeb and Yorick Hardy has alot of fun problems in it. It's the kind of book thats good to read on a bus, or an airplane.

Re:If Schroedinger is anything to go by. . .

[leonardluen]

why is the cat both dead and alive? why can a bit be both one and zero? i don't understand this and would like to hear an explanation that makes sense.

why does it need an "observer"? what exactly is an "observer"? how do we know this is the case? seems to me that the cat is either dead or alive how can it be both? you open the box and find the cat dead or alive, so how do you know it was in some other state before "observing" it? this all seems counterintuitive to normal logic so why should i believe it is true?

last time i asked this i was modded a troll, and was flaimed to death over this new religion that i am supposed to take on faith without any proof. i am merely looking for an explanation to something i don't understand.

Re:If Schroedinger is anything to go by. . .

[Esion Modnar]

the cat stays alive or dead once you open the box

Unless it's been reported alive or dead on Fark. ("The cat, once thought dead, then alive again, then dead, is actually, alive... for now. Quantum physics make my head asplode.")

Re:If Schroedinger is anything to go by. . .

[TeatimeofSoul]

The thing is, certain objects, like spin 1/2 particles, but very much unlike a cat, can be observed in more ways than one.

I'll start by describing a classic experiment (in the sense that it has historical interest, not that it belongs to classical theory). To observe the direction of a spin, you let the particles drift through a magnetic field, and see how their path deviates. It turns out that the result is always either "up" or "down" (both along the magnetic field). Half are up and half are down. According to classical theory, there should be an even spectrum between up and down. Now, put another magnetic field, at right angles to the first one, in the path of just those particles whose spin were, say, up. Along the new direction, of the second magnetic field, the particles will again be either up or down. If the second field had been along the first one, they would all have been up, and if it had been in the opposite direction, they would all have been down.

Quantum mechanics accounts for these results, in a very elegant way. However, science is not the search for truth but for facts (as Indiana Jones said), so if you really don't like it there may be some hidden-variable theory out there for you.

Please note that the "up" and "down" states have different energy content. So, in observing the particles you have interacted with them, supplying energy to half, and taken energy away from the other half. This is the "observer" from the point of view of the particles, the person who supplies, or takes away energy (with no control over what happens to any individual particle).

Whenever someone talks about superposition of states, remember that that means nothing if they haven't defined what observations they're intending to make, and if they're only making one observation, it's a waste of time. Like the dead-or-alive cat. Obviously, when you open the box, it's either dead or alive, end of story.

I should point out that the cat-story originally involved a phial containing poisonous gas, which would open if a radioactive particle decayed. It was told in response to those who claimed that quantum mechanics ruled the world of atoms, but did not influence the "real" world. To shed light on quantum mechanics itself, it is, however, utterly useless.

To make it interesting one would have to add a second observation to the story, one which doesn't commute with the first one - meaning that the definiteness of the results of the first observation is in conflict with that of those of the second. (Like with the magnetic fields at right angles. There's a conflict between a particle being definitely up in the first, and in the second one.) E.g. if there's a second observation, not commuting with the first, which tells you if the cat is tabby or black. Results of these observation might go: alive, tabby, dead, tabby, tabby, alive, black... (Never two different states of colour of livelyness next to eachother.) If this is silly, that's because of the demand that the second observation, whatever it is, not commute with the dead-or-alive observation.

Re:If Schroedinger is anything to go by. . .

[leonardluen]

i didn't use any such terms the last time i was flamed, that is what gave me the impression it is a "new religion" they want me to take it on faith without any explanation...and apparently you don't dare say anything against it or you will have to face the /. inquisition.

capitol letters? i don't see any of those on my keyboard

Re:If Schroedinger is anything to go by. . .

[leonardluen]

I'll start by describing a classic experiment (in the sense that it has historical interest, not that it belongs to classical theory). To observe the direction of a spin, you let the particles drift through a magnetic field, and see how their path deviates. It turns out that the result is always either "up" or "down" (both along the magnetic field). Half are up and half are down. According to classical theory, there should be an even spectrum between up and down. Now, put another magnetic field, at right angles to the first one, in the path of just those particles whose spin were, say, up. Along the new direction, of the second magnetic field, the particles will again be either up or down. If the second field had been along the first one, they would all have been up, and if it had been in the opposite direction, they would all have been down.

that is all fine and well, but if i understand the experiment correctly, i don't see why it needs any special theory to explain the results.

for instance lets look at the way the earth spins, earth spins in all 3 dimensions. first it spins along its axist, but that axis also precesses, and thus the axis of spin is not always facing the same direction.

it seems any spinning object could exhibit these same properties.

thus lets say you try to determine how a particle is spinning. lets say you set up this equipment as close as possible to be exactly perpendicular to it's axis of spin...you measure it once, and you find out that it is spinning up...you then wait a few seconds and measure it again...however this time you find it is spinning down

how could this be? in the experement above the particle is primarily spinning either left or right in relation to our measuring instrument, but it will have a slight component of up or down due to the precession of the axis and the amount of this up or down spin will gradually change over time...possible to the point that at one time we measure it it appears to be spinning up, and the next time it appears to be spinning down.

also, unless there is some csomic rule i don't know about all object can spin in 3 dimensions, and so it isn't as simple as just if the spin is up or down...the spin could also have a component of left or right to it. so it is not surprising that when you add a second perpendicular magnetice field that you find that the particle was spinning up and to the left... or up and to the right. so i don't see anything that doesn't seem to fit within normal physics, unless i misunderstood the expirement you outlined.

Re:If Schroedinger is anything to go by. . .

[MenTaLguY]

why is the cat both dead and alive? why can a bit be both one and zero? i don't understand this and would like to hear an explanation that makes sense.

While I'm not sure there is an explanation that makes intuitive sense, it does appear to be the way the universe works at small scales.

Schroedinger's thought experiment was intended to illustrate the weirdness of the issue by tying the state of a macroscopic object (a cat) to a quantum state (the decay/not decay of the particle), mainly. It's not a realistic experiment because you couldn't isolate the macroscopic contents of the box from the outside world sufficiently (and besides, it's cruel).

But, real experiments do demonstrate that quantum stuff consistently behaves in really bizzare and counterintuitive it-is-but-it-isn't ways.

One famous example is the oft-repeated "double slit" experiment (hopefully I won't mangle the summary too much).

You remember light-as-waves? If you take a coherent light source (i.e. a laser) and shine it onto a screen through a mask with two small parallel slits in it, you will see a pattern on the screen resulting from the two interfering wavefronts.

That's simple enough. But light is also particles (photons). You can put a filter between the lazer and the mask that only allows one photon at a time to dribble through. Now you have individual photons going through the mask, and you see individual spots as they hit the screen. Intuitive enough.

But it starts to get weird. If you measure the brightness of those spots, though, they still follow the brightness of the interference pattern. That would suggest that the photon is going through both slits at once and somehow interfering with itself. Hmm, that's not very intuitive.

But, okay. We can test that by using detectors at the slits to note the photons as they go by. Hmm. No, each photon is only going through one slit or the other, not both at once. So why are we getting the interference pattern? Wait, where did the interference pattern go?

Huh. We stop observing which slit the photon is going through, and the interference pattern comes back (i.e. it effectively went through both slots). We start observing again, and it starts "picking" one or the other slot again...

Basically it looks as if, to employ a gross anthoropomorphism, on quantum scales the universe is "lazy", and only commits to a specific choice if it has to (because somebody is watching). No, that's not intuitive, and no, we have no clue how this happens exactly (although we're getting better at describing it and exploiting it for practical purposes like primitive quantum computers), but that's what happens.

why does it need an "observer"? what exactly is an observer"?

Physicists are wrestling with that one. We don't really know. A person directly observing the quality being tested (directly or via instrumentation) seems to be sufficient, but not necessary.

That's one of the downsides of the "Copenhagen Interpretation", which is the most common interpretation of these phenomena -- that an observer observing "forces" the universe to make a "choice" (the grossly anthropomorphic word choice is mine though -- the actual way of putting it is that the act of observation "collapses the wave function").

There are other interpretations, too, that don't require a privileged position of "observer", but they have other very awkward quirks.

this all seems counterintuitive to normal logic so why should i believe it is true?

Certainly you shouldn't accept it just because someone says so, or because a few experiments suggest it might be true. In this case, though, the experiments have been repeated too many times by too many different people for the weird results to be the result of experimental error though, and also experiments designed to disprove these behaviors have fai

Re:If Schroedinger is anything to go by. . .

[MenTaLguY]

Something to bear in mind is that when we talk about particle spin, "spin" is a metaphor. There isn't an actual rotation of a material object involved.

"spin" is just a label we've adopted for an abstract property of particles for which we don't have a good name otherwise. It becomes more obvious in e.g. quantum chromodynamics, where we use labels like "color" to describe particles.

Sadly, it's all too easy to mistake the map for the territory here.

In physics, even the notion of particles is a metaphor for stuff happening in specific places (at least when we're looking) and existing in discrete quantities, but taking the metaphor too far (e.g. reasoning as if they were actually tiny little solid spheres) eventually leads to conclusions that don't match what happens in the physical world.

And, that's what actually matters in the end. Not my assertions or those of the GP, but what experiments demonstrate about how the physical world behaves. The metaphors are just descriptive.

Re:If Schroedinger is anything to go by. . .

[MenTaLguY]

Yeah, it makes me sad because although you don't seem to have much science background, you are actually asking scientifically-minded questions. :/

Although I don't think it's conscious, lot of people really do end up trying to treat scientific issues in religious terms. Witness BOTH sides of the creationism/evolution/etc flamefests.

Re:If Schroedinger is anything to go by. . .

[leonardluen]

i guess i am glad i am macroscopic, the world makes much more sense that way.

Re:If Schroedinger is anything to go by. . .

[MenTaLguY]

i guess i am glad i am macroscopic, the world makes much more sense that way.

Heh, seriously. I guess it's what we're used to though.

Re:If Schroedinger is anything to go by. . .

[exp(pi*sqrt(163))]

I think that is the best summary I've read so far! Basically they are analog computers. And this is why I'm also so skeptical of them - I doubt you can do analog physics with the required degree of accuracy, even with error correction. Every paper I've seen on quantum error correction assumes a special form for Hamiltonian of an external interaction and yet an analog system is never like that. There are always other terms interacting, and in the case of QM those terms grow exponentially and swamp the data you really want.

Re:If Schroedinger is anything to go by. . .

[TeatimeofSoul]

I see now that I could have been clearer.
The amount of deviation of the particles from their flightpath is proportional to the component of spin parallel to the magnetic field. So classically you find that, if e.g. the spin is perpendicular, there will be no deviation. However, experimentally, half deviate one way, _all with the same amount_, and vice versa with the other half.

Before the observation, the spin could be in any direction, and it might also be precessing, but the observation causes it to be along the magnetic field, or against it.

Yes, the precession could hypothetically fool us by always pointing the spin along, or against, the direction we've happened the choose... Neat trick.

Re:If Schroedinger is anything to go by. . .

[Veinor]

Actually, it wouldn't be the whole set of C x C. It resides in S^3, i.e. the set of all points (a,b,c,d) so that a^2+b^2+c^2+d^2=1, a,b,c,d in R.

Proof: The probability amplitudes for 0 and 1 must sum to 1. Now, the probability amplitude is the square of the norm of the (complex) probability. This means that if the complex numbers are a+bi and c+di, then |a+bi|^2+|c+di|^2=1, or a^2+b^2+c^2+d^2=1, exactly the equation for S^3.

I know, I know... I'm such a geek.

Re:If Schroedinger is anything to go by. . .

[leonardluen]

i am merely trying to find an explanations that already exists without reinventing things. it may very well be that we don't have enough information to explain some of this phenomena, but some of the ideas of quantum mechanics still seem almost too mystical....sort of like alchemy or astrology...which i might add led to chemistry and astronomy and so both were just a stepping stone to future advancements even though they were filled with many misconceptions at the time. so it doesn't mean it is invalid, only that we have more we need to learn, and that it may very well be possible that some of the things we currently think about it really aren't valid.

Re:If Schroedinger is anything to go by. . .

[MenTaLguY]

Yes. Quantum mechanics should eventually get superceded by something else which accounts for physics under a much wider range of conditions. As you say, doesn't mean QM was wrong as such, just that there are more complete descriptions out there. And physicists are still looking.

But I'd be careful making an alchemy/astrology comparison... A key difference between alchemy/astrology and chemistry/astronomy is that the former are occult systems where metaphors are evaluated subjectively, and the latter are scientific fields where knowledge is shared freely and metaphors are tested by repeated and independent experiments.

Now, prior to the scientific revolution, they were the same thing.

What happened with the development of the scientific method was that even though they started in the same place, chemistry/astronomy rapidly differentiated itself because the most erroneous ideas didn't last long under empirical scrutiny. In response, alchemy/astrology necessarily rejected the idea of an objective reality that could be empirically tested.

So, it doesn't really matter whether a theory seems subjectively mystical or not (though that can be a warning sign). The important questions are "can it be tested?", "has it been tested?", and (as you very rightly point out) "is it the simplest theory?" (i.e. have the simpler theories been tested and failed?)

In the case of particle spin, it's been observed that, although much of the math is superficially similar to the angular momentum of a spinning sphere, particle spin is quantized.

Electrons, for example, have only been observed with two possible "spin" directions (called "up" and "down", though there's no reference to an absolute up and down), and no possible intermediate angles between them, which appears to hold true regardless of where they are observed from[1].

This (among other things) indicates that thinking of them them in terms of literal rotating spheres (which can have any spin orientation), while superficially simpler and more intuitive, isn't useful.

---

[1] Check out the Stern-Gerlach experiment for one way to demonstrate this. If there were intermediate spin states, the electrons would fan out rather than exactly split into two neat streams.

Re:If Schroedinger is anything to go by. . .

[MenTaLguY]

Meh, I didn't read the GP post carefully, and (except for the alchemy bit) sort of re-covered the same material. Sorry about that.

Re:If Schroedinger is anything to go by. . .

[TeatimeofSoul]

Well, you should really start looking in to hidden-variables theory. I don't know where it stands these days - it keeps popping up in slightly different forms, only to get shot down.

My personal opinion is: What's so understandable about classical magnetism anyway, or Newtons law of gravity - action at a distance, that's just weird! Might as well choose whatever weird theory, that accounts for what you see in the simplest mathematical form.

Re:If Schroedinger is anything to go by. . .

[Alsee]

"Analog" is really a poor way of describing a quantum state. It is not analog between the two states, it is in all states at the same time. It is just that the strength of each state in the mixture can be different. You can have 25% of it be all the way 'zero' and 75% of it be all the way 'one', and that is extremely different than the analog value 0.75.

-

Re:If Schroedinger is anything to go by. . .

[exp(pi*sqrt(163))]

"Analog" is really a poor way of describing a quantum state.

No it's not. It's exactly right.

it is in all states at the same time

Don't let that metaphysics stuff distract you from the actual issue. The state of a single isolated qubit is defined by a complex vector of norm 1. There's no beating about the bush. It's as analog as, say, a voltage, and its time evolution is given by a differential equation. Yes, when you come to observe it you'll measure a zero or one, but that doesn't invalidate that its internal workings are basically analog.

Re:If Schroedinger is anything to go by. . .

[Alsee]

Ok, there was a little tripping over language there.

It was quite a while ago that I read the details of the quantum error correction system. I only superficially understood it and how it works, but the experts do seem to be in solid agreement that it will work. It will be facinating to see how it turns out and exactly what it can do once we can put the peices together.

-

interesting idea

[kae_verens]

If I understand this correctly, this would be similar to holding an array of marbles in the square "holes" in a tennis racket. I wonder if the laser lattice affects the atoms in any way other than keeping them in one position? Is there a danger of the lasers changing the atom in a way that renders the qubit useless?

Re:I am Ready

[AKAImBatman]

Don't panic! I'll go get my towel.

Original News Release

[Milalwi]

The original news release, which has an animation to support the story is available at the Ohio State University Research News site.

Milalwi

Re:Original News Release

[MicroBerto]

As a Buckeye (about to graduate in ECE), this is great to see. Most of our best research is done in the medical field, where we have world-reknowned centers. It's good to see our physics and computer guys stealing some thunder. We're not the MIT of computing and physics, but there's certainly quite a few brains here.

Re:Original News Release

[RailGunner]

I also like the research done on the football field.
Muck Fichigan - GO BUCKEYES!

Re:Original News Release

[MicroBerto]

Hahaha, nice! I just hope it goes better than during the spring game

I just ordered my Texas ticket through a friend's student ticket. I'll be living in Austin starting in July, but you can rest assured that i'll be talkin plenty of friendly smack for that game!

Re:Original News Release

[RailGunner]

What game? It's not going to be a game, it's going to be an asskicking. Bob Stoops at OU has proven time and time again that the way to beat Texasis to contain Vince Young, and make him try to beat you with his arm and not his legs.

Tressel knows this, and with the secondary Ohio State has (not to mention the offense) Texas is toast. Plus, Mack Brown is as big of a moron as Lloyd Carr is (hooray Lloyd - 1-3 vs. Tressel).

I live in Texas - these fans down here sure are proud of the vastly overrated Big 12... who the Big 10 consistently stomps the hell out of in bowl games.

OU struggled with an Oklahoma State team that the Buckeyes crushed. Texas struggled with a Michigan team that the Buckeyes manhandled... this could be a National Championship year for the Buckeyes, and I'm going to love every minute of it.

Someone please clarify

[karvind]

From the article: "We're pretty sure we can trap atoms -- the first step towards making a quantum memory chip," Lafyatis said. A working computer based on the design is many years away, though, he cautioned. In fact, Christandl suspects that they are at least two years away from being able to isolate one atom per trap -- the physical arrangement required for a true quantum memory device.

1. What is the working principle behind this (mechanism of trapping) ?

2. Are these experiments performed at room temperature ?

3. How do they ensure they have trapped one "desired" atom and not more atoms and not some other impurity?

4. How is the laser prevented from interfering with lattice (non-desirable interactions) ?

5. What is the decoherence time which governs if you can really do any computation before the result is lost ?

This is indeed an important step forward. But alas the student is graduating in august and I hope there is someone to followup on this work:

Theoretically, if they release the atoms above the chip in just the right way, the atoms will fall into the traps. They hope to be able to perform that final test before Christandl graduates in August.

Re:Someone please clarify

[nihilogos]

1. What is the working principle behind this (mechanism of trapping) ?

They usually trap ions which are charged, and so can be trapped with an electro-magnetic field. A slight subtelty is that you need an oscillating electric-magnetic field which is exactly what the laser provides.

2. Are these experiments performed at room temperature ?

Hell no, unless you have a holiday house on Triton. They are cooled to almost absolute zero, because otherwise the ions are just moving too quickly to be trapped.

3. How do they ensure they have trapped one "desired" atom and not more atoms and not some other impurity?

A variety of techniques are available to detect individual atoms. One of the most common is to focus a laser tuned to a resonant frequency of the ion at one of the lattice points, the ion will then flouresce and the resulting photons can be detected.

4. How is the laser prevented from interfering with lattice (non-desirable interactions) ?

The laser is the lattice - it's an 'optical lattice'.

5. What is the decoherence time which governs if you can really do any computation before the result is lost ?

I'm not sure anyone knows just yet.

Re:Someone please clarify

[smeek]

Okay, normally I wouldn't bother responding, but I feel compelled to correct a number of false statements in this post

1. What is the working principle behind this (mechanism of trapping) ?

They usually trap ions which are charged, and so can be trapped with an electro-magnetic field. A slight subtelty is that you need an oscillating electric-magnetic field which is exactly what the laser provides.

NO, they are not trapping ions. I doubt it is even possible with this scheme. With static fields it is impossible by Earnshaw's theorem, but there's always a possibility with AC fields. In any case, they are not even making use of the AC nature of light, but rather they are creating, using counterpropagating beams, nodes where the electric and magnetic fields are always zero. Away from these points, there are non-zero fields. The atoms they are trapping are neutral, but because they have a non-zero total angular momentum, they have a magnetic dipole which in the presence of a magnetic field, produces a dependence in energy on magnetic field strength, independent of direction. What this means is that, if the atom is a a position where there is no magnetic field, but is immediately surrounded by regions with non-zero field, the atom is going to tend to remain at the lower energy zero-field point.

2. Are these experiments performed at room temperature ?

Hell no, unless you have a holiday house on Triton. They are cooled to almost absolute zero, because otherwise the ions are just moving too quickly to be trapped.

No, the atoms (not ions) themselves are usually at milli- or microKelvin temperatures, but their surroundings rarely need to be cooled. It is fairly straightforward, through laser cooling to cool the atoms, and because this is all done in an ultrahigh vacuum, there is almost no interaction with the room temperature walls, so cooling the macroscopic objects in the experiment does little to improve the setup.

3. How do they ensure they have trapped one "desired" atom and not more atoms and not some other impurity?

A variety of techniques are available to detect individual atoms. One of the most common is to focus a laser tuned to a resonant frequency of the ion at one of the lattice points, the ion will then flouresce and the resulting photons can be detected.

Nevermind that two bosonic atoms in the translational ground state will look exactly the same as one for the purpose of laser-induced fluorescence. In reality, it is very difficult to distinguish 1 atom in a trap from n atoms in a trap. I have yet to see any papers describing how to do so.

4. How is the laser prevented from interfering with lattice (non-desirable interactions) ?

The laser is the lattice - it's an 'optical lattice'.

The optical lattice is produced because, with beams propagating in opposite directions, there will always be fixed points where the field is zero, evenly spaced by half a wavelength. Assuming you meant, why the lasers to not produce undesirable interactions with the atoms they are containing, this is because the lasers are tuned to wavelengths that will not interact with the internal electronic structure of the atom.

Re:Someone please clarify

[nihilogos]

I stand corrected.

Related article

[c0ldfusi0n]

Physicists could soon be creating black holes in the laboratory

When shall we get pet dark holes?
Imagine cleaning the house with one of these around!

In related news...

[Etherwalk]

> Scientists at Ohio State University have taken a step toward the development of quantum computers by making tiny holes that contain nothing at all

In related news, Ohio State University has recieved research funding from the NSA to perform Ear Exams on all members of Congress twice a year...

A Different Kind of Quantum Computing

[moslevin]

It sounds like the terminology is confusing a few people here. As I understand it, there are two kinds of quantum computer being researched- the one that everybody seems to be familiar with (ie. the ones that can solve cryptographic problems very quickly), and the other kind, which involves using the physical properties of individual quanta to create quantum wires, transistors, and gates to form clocked, general purpose architectures. This article is talking about the second type of QCs. Currently, the biggest challenges (from what I've read) associated with implementing the second type of QCs has to do with manufacturing tolerances required to create quantum wells capable of keeping quantum data encapsulated and determinsitic. The other challenges include finding ways to clock these quantum circuits, and ways of inputting/outputting the data. So, from my interpretation, this article is really just talking about some potential solutions for aspects related to the second type of QCs I mentioned.

Re:A Different Kind of Quantum Computing

[moslevin]

Like any good design problem- it really depends on what the priority is. In terms of some simple classes of circuits, you probably could get away without clocking anything- just like certain types of digital or analog circuits today don't require a clock. But when you make the leap to anything state driven, you would absolutely need a clock. I suggest looking at the research of the atips group. With the sophistication of what they're trying to develop using the same type of technology, yes, you need a clock: http://www.qcadesigner.ca/tutorials/QCATutorial.ht ml

I wonder...

[FreakyControl]

One strategy for making them involves packaging individual atoms on a chip so that laser beams can read quantum data.

I wonder if reading the state on one QC will inadvertently change the state on a QC somewhere else in the world. Of course, a worst case scenario would be if someone were trying to get there pR0n real fast and made that alien ships QC navigational system fail...

Re:I wonder...

[SolFire]

Acutally that won't happen because if it happend, it would imply information travelling faster than light, and that does not happen. Even if you have a pair of perfectly entangled qubits (called an e-bit), and you seperate them by a great distance and perform a quantum operation on the first qubit, the measurment outcome of the first qubit will not affect the measurement outcome of the second qubit.

The idea of Quantum Teleportation has been misunderstood. Quantum Teleportation is not like the Star Trek transporters. Quantum Teleportation is a method of sending a qubit to another person. In order to do this you need to share an e-bit. Ex. Alice has a qubit Y she wants to send to Bob. Alice and Bob also share an e-bit E (which is a perfectly entagled pair of qubits 1/sqrt(2)(|00>+|11>). Alice performs a controlled-not operation on her part of the e-bit Y, then she does a Haddamard transformation (Quatum Fourrier Tranform on 1 bit) on the qubit Y, then she measures both the qubit Y and her part of the e-bit E. At this point we have two classical bits 00, 01, 10, or 11. She then sends this to Bob. Bob the performs a controlled-not on his part of the e-bit Y based on the first bit, and a controlled phase-flip based on the second bit at which point Bob's qubit that he now has is Y. This process perfectly sends a qubit from Alice to Bob, but the key part of this method that needs to be remembered is that the two classical bits that Alice measured had to be sent to Bob. Without these bits Bob would not be able to get Y and sending the classical bits, takes the usual ammount of time.

What's even cooler is that if Alice's qubit Y had been entangled with another qubit X, the entanglement is preserved after the QT process so that the qubit Bob has is now entangled with X.

Disclaimer: I am not a quantum physicist. I am a recent computer science grad who just took a course on Quantum Computing. Just one.

is that because of

[Prince Vegeta SSJ4]

the Quantum Leap in eyecandy bloat?

The Law.

[k96822]

...and this is why Moore's Law will continue, even though Moore himself says that it won't. Never underestimate the cleverness of the Human.

Re:The Law.

[Quiet_Desperation]

Never underestimate the cleverness of the Human.

*cough*fusionpower*cough* The eternally "just around the corner" technology.

Hey, I tease mankind. :)

Re:The Law.

[k96822]

That, and flying cars. Where are our flying cars? Oh wait, there was a recent article on that one. Still, I see no cars in the sky!

Re:tiny chips, tiny problems

[karvind]

Does anybody really know exactly how atoms and sub-atomic particles are going to behave in less-than perfect environments? What about gamma-ray bursts from stars and nuclear emissions from our Sun? Will these possibly have an adverse effect on a chip that is running on the atomic level?

One of the key to making things at nanoscale is to have fault and defect tolerance. With billions of elements in the system, you are bound to get manufacturing defects as well as many run-time defects. Even in modern DRAMs they have redundant columns of memory cells to improve the yield by swapping the defective ones with spare ones. FPGA(Field Programmable Gate Arrays) offer in-circuit reconfigurability. HP showed Teremac few years ago which had millions of defects yet it worked just "fine" by detecting the defects and reconfiguring around it.

In short there will be sources of errors and faults in these systems, but there are various ways to get around it. Also in quantum computing, you can encode your data in such a way that it is immune to noise (atleast to certain extent) and is called Quantum error correction.

But also remember that science is not just about destination but also the journey. Even if practical quantum computers are never built, we are likely to learn many interesting aspects which may be used elsewhere.

Re:tiny chips, tiny problems

[aziraphale]

"How about our Scientists rescue the Hubble Telescope first, something we know works, then worry about the quantum chip later."

No, but first, our scientists have to clean their teeth, then our scientists will be asleep for the next eight hours. Once our scientists have got up in the morning, they'll have a bowl of cheerios and then read the paper for a bit. Then maybe they can tackle the Hubble telescope problem (although the fact that all n million of them are trying to write on the blackboard at the same time does mean they won't make much progress. And the biologists have to sit around twiddling their thumbs because there's not much they can do to help). After Hubble, there's some promising work on cancer they need to finish up, before they can get on with a bit of geology.

Hopefully, someday soon, our scientists will realise that they can get much more done if they allow small groups of themselves to concentrate on different things, so they can make progress in different fields at the same time. In the mean time, though, you're right. They're all wasting their time on this pointless quantum computing nonsense.

Re:There are still steps to take before quantum...

[advocate_one]

Diamonds have the highest conductivity rate of any known metal, which makes them perfect candidates for traditional computing. You may think "oh, but they're so expensive," but this isn't necessarily true. Natural diamonds are expensive, but this isn't due to its scarcity.

Diamonds are not a metal... and Diamonds have the highest thermal conductivity... the last thing you want here for semiconductor devices is a substrate with the highest electrical conductivity... you want a very good insulator, which also gets heat away very quickly... this is where Diamond layers come in... not solid machined diamonds, but diamond deposited or grown into a thin layer...

Re:I am Ready

[CoffeeJedi]

some information you may be interested in:
Time Cube

(sorry, had to do it!)

Seinfeld

[micromuncher]

Tiny holes... that contain nothing at all. An article about tiny holes. An article about nothing. Reminds me of Seinfeld.

Qubit meet Q*bert

[digitaldc]

From the Qubit article you linked to:
"During the correction procedure, the entanglement between the system and its environment is transferred to an entanglement between the measuring apparatus and the environment. The qubit is actively isolated from its environment by means of this carefully controlled entanglement transfer."
It continues....
"The main proviso to all the above is that the correction process can itself be carried out without errors. This is clearly a huge assumption. It is probably reasonable in the context of quantum communication [7,8], since there one eventually wishes to measure the communicated qubits, and the bulk of the error correction can be carried out on the classical information obtained after the qubits are measured. The context of quantum computing is another matter, however, and it remains to be seen whether quantum error correction can be made sufficiently robust against noise during the correction process itself. Thus quantum theory may still rule out the possibility of a powerful quantum computer."
The error correction process for the Qubit must not have errors itself - there inlies the main problem. I am all for quantum chips and the benefits they may reap, I just hope they aren't used to develop more powerful weapons of mass destruction. If the quantum chip is developed fully, I can see it being used for Holographic-3D projection of images. Also for artificially intelligent robots that can be sent into hostile environments such as Mars or Titan and provide quick and accurate feedback on their observations and experiments.

Void?

[Netsensei]

This is going to give a total new meaning to the 'void' keyword in high level programming languages like Java, I suppose.

Re:Void?

[Netsensei]

Same goes for /dev/null too...

Obviously

Re:Void?

[argent]

You're notgoing to program quantum computers in anything like Java. The languages currently in use that are most likely to work well on these kinds of systems are things like Prolog.

No, there could be tiny gophers

[MichaelPenne]

in there!

Then they would be tiny holes that contain gohphers, you see?

Fore!

RIAA Loses

[Billygoatz]

I for one am very excited.

I have thousands of hours of mp3s.

My Quantum computer could represent (and play)all possible kickass songs, while all crap songs (Rap HipHop) would be canceled out through destructive interference.

The best thing of all is if the RIAA raids me. Simply observing quantum metallica destroys or disrupts the data.

Factoring is NOT known to be NP-complete

[Catullus]

In fact, it would be very surprising if it turns out to be NP-complete, as it is in NP intersect co-NP. Also, no efficient quantum algorithms are known for NP-complete problems, and it is generally suspected that quantum computers won't be able to solve them efficiently. For example, see this semi-technical paper.

You had better get that right in your undergrad thesis ;)

Re:Factoring is NOT known to be NP-complete

[ortholattice]

While I have not read the paper you mention completely enough yet to understand its argument, let me point out the obvious fact that nature, by definition, "simulates itself," i.e. is its own computer. Now, the processes involved are extremely complex; just to simulate the processes going on inside of a single atom can take years of computation time on an ordinary computer, yet it happens essentially instantly in actuality. Is the problem of simulating nature on a submicroscopic level NP-complete? I'm not sure, but certainly it's way beyond the realm of what present-day computers can do. The question is, can we somehow harness this incredible built-in computational power to solve more general problems?

Re:Factoring is NOT known to be NP-complete

[marcosdumay]

Is the problem of simulating nature on a submicroscopic level NP-complete?

First, I have to ask: What problem? As far as I know, simulating the interation of a certain number of particles may be NP complete if you take into consideration the number of particles. But if this number is fixed, it is not. I am not sure, but I think it is P.

So, all you got is a computer that becomes much more fast than conventional ones when its size increase, but you still don't have an efficient way of solving NP complete problems.

Re:Factoring is NOT known to be NP-complete

[Planesdragon]

While I have not read the paper you mention completely enough yet to understand its argument, let me point out the obvious fact that nature, by definition, "simulates itself," i.e. is its own computer.

You're misusing that first word.

A "simulation" is a testable model of something, usually created for a specific kind of testing, that specifically is NOT the thing itself. By way of example, consider "simulating" adding numbers on a computer chip. Most of the time you wouldn't bother doing it, because it's easier just to actually add them.

But you could "simulate", oh, a computer chip running a very-complex program, just by having it do something that's needlessly complex. (Like, oh, performing random operations on a random number of a random size.)

When you start dealing with Quantum Mechanics, it's important to stop every now and again, and remember that what we have for QM is a *simulation* -- i.e., in certain fundamental ways it's simply wrong, but the wrongness is OK because we don't need to know everything about how a process works for that process to work, or even to come up with a new process.

Re:Factoring is NOT known to be NP-complete

[Alsee]

The question is, can we somehow harness this incredible built-in computational power to solve more general problems?

This is the exact question he is addressing. Whether there is possible to arrange anything in the universe that could represent a problem and allow it to "simulate itself" and look at the result to see the solution of that problem.

For example he explains that quantum mechanics does not appear to allow the solution of NP problems. He does not proove it impossible, but he does rule out most approaches and he maps out what unsolved (and apparently insoluable) problems would need to be solved to accomplish it.

At the end he hypothesizes a law of nature that the universe cannot solve NP problems. A very interesting paper and a very interesting hypothesis.

-

Re:tiny chips, tiny problems

[wfijvvz]

How about our Scientists rescue the Hubble Telescope first, something we know works, then worry about the quantum chip later.

I was going to cure cancer, but I decided to refresh slashdot's front page instead.

My favourite Quantum Computer...

[TrickFred]

My favourite Quantum Computer, created from 10,000 networked Protologic 68000s.

http://www.darwinia.co.uk/

Oh boy.

[geek_xyu]

That is dead on. Quantum Leap rules. But you didn't metion Al or Ziggy. Many of the leaps wouldn't have been successfull if it weren't for them.

Re:Oh boy.

[ikkonoishi]

Without Al and Ziggy to tell Sam what to do none of the leaps would have been successful.

-1, Insensitive

[drsquare]

I would love to see a 747 parallel park in Manhattan.

Didn't they try that back in 2001?

Re:-1, Insensitive

[darthdavid]

The planes that hit the WTC were 767s you dumbass.

Re:-1, Insensitive

[Bobsledboy]

-1, Whoosh!

The obligatory

[TheAvatar666]

My quantum computer is REALLY fast but I don't know where it is.

Wait.... Holes In Laser Light?

[Wandering Wombat]

The holes - dark spots in an egg carton-shaped surface of laser light - could one day cradle atoms for quantum computing." This means that the surface of laser light is egg-carton shaped. Someone may want to run this through a basic grammar checker, and try again (unless I'm totally mixed up on what light looks like at great magnification ;))

Re:Wait.... Holes In Laser Light?

[Wandering Wombat]

Ahhhh, interference patterns. I know laser light doesn't have a 'surface', but I just didn't understand how a beam of light could have "pockets". It makes a bit more sense now.

Sorry.... I Didn't Hit Preview...

[Wandering Wombat]

The holes - dark spots in an egg carton-shaped surface of laser light - could one day cradle atoms for quantum computing."

This means that the surface of laser light is egg-carton shaped. Someone may want to run this through a basic grammar checker, and try again (unless I'm totally mixed up on what light looks like at great magnification ;))

Re:Awesomeness

[Wandering Wombat]

I don't see how it could crack into a computer any faster than a modern computer, since the number of times you are allowed to try and crack a machine is based on the speed of the machine being cracked, isn't it?

wait a minute

[commodoresloat]

Won't the smoke escape through all the tiny holes?

Re:wait a minute

[mrogers]

Don't worry, it's a quantum computer so if you observe the smoke escaping then it collapses. You'll just need to keep one eye on your CPU while you're working.

Quantum computing is a fad/here to stay

[Urusai]

It will fade out/grow bigger over time and nobody will care/deny its greatness. What a bunch of maroons/geniuses!

Re:Awesomeness

[egomaniac]

I don't see how it could crack into a computer any faster than a modern computer, since the number of times you are allowed to try and crack a machine is based on the speed of the machine being cracked, isn't it?

Not always. For instance if you have access to the /etc/passwd file, all you have to do is find a password which hashes to the same value as the entry in the passwd file, and you can do that on an entirely different machine.

Public key algorithms are also vulnerable, as the private key can be likewise be found without talking to the target computer at all. I'm sure many other such systems are vulnerable.

wait....

[norkakn]

So are these holes real or not??

(if you don't get it, don't mod it)

Re:Awesomeness

[Wandering Wombat]

Good point. I am not a cryptologist, but as an amateur I figured that it would be simple enough to keep all software that could be easily cracked on the server side, safe from attacks. Thats just me, though, I'm sure the people who design these systems know better.

Re:tiny chips, tiny problems

[mdielmann]

If MOO II has taught me anything, it is that as a species you can only figure out one advancement at a time (unless you're the psilons, and we're not).

Re:Great principle - Funny?

[lcsjk]

I don't think first poster meant to be funny. I also think he has trouble with sentence structure. Maybe in a rush to be first poster.....

"Surface of Laser Light"

[alcmaeon]

What exactly is a "surface" of laser light? The article didn't seem helpful in this respect.

RTFContext

[PenguiN42]

From TFA: "In principle, quantum computers would need only 10,000 qubits to outperform today's state-of-the-art computers with billions and billions of regular bits," Lafyatis said.

Sure, for specific classes of problems that quantum computers are really really good at. But the whole discussion in this thread was about quantum computers simulating classical computers doing their everyday, mundane, classical computer things.

The quote shines no light on the actual question: How powerful of a quantum computer would you need to completely simulate a classical computer of a certain size/amount of processing power?

Re:Awesomeness

[egomaniac]

Good point. I am not a cryptologist, but as an amateur I figured that it would be simple enough to keep all software that could be easily cracked on the server side, safe from attacks. Thats just me, though, I'm sure the people who design these systems know better.

You're mostly correct. There is absolutely no reason for ordinary users to be able to read the /etc/passwd file or other such hashed password files, so on properly-configured machines you can't apply that particular attack.

The public key problem, though, is unsolvable. By their very nature they require giving you the public key, and the public key + massive amounts of computational power == private key. They rely on the fact that massive amounts of computational power aren't readily available, but quantum computers will take care of that little wrinkle.

I can't wait to be able to start signing software using, say, Microsoft's private key ;-).

Re:Awesomeness

[aka1nas]

The Grandparent poster had it right. Public key-based systems would be very vulnerable to being cracked by quantum computing. By their very nature, the public key has to be known by all and they work on the principle that it would take prohibitively long to brute force the corresponding private key (Millions and millions of years with a supercomputer or a huge distributed network). Quantum computing would really screw that up and we would have a lot of critical security systems that would need to be replaced quickly if someone develops practical quantum computing.

Damn Butterflies.

[purduephotog]

The problem with the current quantum computer research is there are always butterflies in China flapping their wings ... interfering with the research done in the US.

Nanomechanical quantum computing

[TheSync]

My money is on nanomechanical quantum computing. Forget all this ultracold gas vapor stuff, it is like vaccuum tubes...

Nothing

[usacoder]

"by making tiny holes that contain nothing at all. " that reminds me of the old moron test: "how much dirt is a hole 2' x 2' x 2'?"

MOD PARENT UP

[coopex]

Good laymans description of qubits.

Question..

[Pepsi__Blue]

I'm no physicist, but isn't this similar to this paper written 5 years ago??? And didn't Scientific American write about a similar expirament withen the last 6 months? I may be mistaken, so I'll try to dig through my pile of magazines later tonight.

See the Animation (.mov and .wmv)

[Anonymous Coward]

Here are posted movies of the experiment

http://researchnews.osu.edu/archive/eggcarton.htm

Re:See the Animation (.mov and .wmv)

[Gate-c]

I am the one who actually made this animation for OSU research communications last week!

Re:Actually PRIMES is in P

[Catullus]

Yes, but FACTORING isn't. They're different problems.

Feels like im wearing..

[mesmartyoudumb]

Nothin at all!

Stupid sexy flanders!

Re:Feels like im wearing..

[mesmartyoudumb]

Haha..Link..

http://stupidsexypsp.ytmnd.com/

Excuse the PSP ejecting a CD..

Not exactly right

[leonbrooks]

The jar is useful because it may contain emptinessm, whereas merely mortal jars get a choice of air or something else.

I'm not clear on how they keep zero-point fields out of the hole. Is it simply too small? Or did they kill off Syndrome too soon?

Sonny boy...

[leonbrooks]

...sitting to my left is a computer that relies on cassette tape storage, at 300 baud and with seek times measured in minutes. You even had to supply your own cassette recorder to utilise this option.

I'm considering ripping some of the tapes into SHorteN files for the fast-approaching day when cassette tapes are no longer available.

A year to read it?

[leonbrooks]

Wouldn't it be obsolete by then? (-:

WTF?

[leonbrooks]

Simply observing ordinary Metallica destroys or disrupts the data in your head. What's so special here?

Re:Awesomeness

[ejhuff]

This is very true, for many systems. I asked about this on sci.crypt some years ago, and received a reply suggesting that some banking industry standards regard the _public_ key as a secret shared between the bank and the customer, with the private key known only by the customer. If so, at least these systems will not fail catastrophically. Factoring the public key is only possible if you know it, so a second failure (bank reveals the secret "public" key) is required before the customer's identity is compromised.

Re:tiny chips, tiny problems

[Wargames]

Notice that scientists eat Cheerios. Notice that you will never see a scientist's picture on a box of Wheaties.

Re:There are still steps to take before quantum...

[NanoGradStudent]

Just two points to clarify in the parents post:

1) Thermal conductivity != electrical conductivity i.e. most ceramics are very good heat conductors, but are very poor electrical conductors (though with the *right* ceramics and some liquid nitrogen or helium, they can, in fact, become super conducting)

2) Pure diamonds are electrical insulators, sure, but they can be doped with impurities to become either conductors or semiconductors.

There were a couple of Slashdot stories last year on the forthcoming 'Diamond Age' of diamond-based semiconductors that had some neat posts (and numerous pages and probably some wikipedia pages that I'm too lazy to look up right now).

Re:Actually PRIMES is in P

[Catullus]

Yes, you're right, I was being lazy. You win.