German Scientists Create 5 qubit Quantum Register

CMan0 writes "In the University of Bonn, a team of scientists has built a 5 qubit register, using cesium atoms trapped by a laser-beam grid, The Register reports. They've been able to install an empty 5 bit register(i.e. all bits 0), change two of them to 1, and later read those 1s back. The next goal is to create an interaction between 2 bits. The full scientific article can be found here in PDF format."

Comments

"What's a qubit?",

[Anonymous Coward]

Noah inquired.

Re:"What's a qubit?",

[Ohreally_factor]

1 qubit = 1.5 feet, which is why they look so awkward when they walk.

Re:"What's a qubit?",

[i.r.id10t]

Actually, that was Bill Cosby - or at least it was part of the act he did at the first Gator Growl he headlined (not hte one in 2002)...

Re:"What's a qubit?",

[maxwell demon]

A qubit (for "quantum bit") is the basic information unit for a quantum computer (just as the classical bit is for classical computers). They are actually two-state quantum systems (just as ... Ok, I'm repeating myself :-))

The point is that quantum systems have properties which are not found in classical systems. For one, they cannot be just in the states "0" or "1" (in the usual notation for quantum states: |0> or |1>), but also in so called superpositions of those states. Such a superposition means that they are something like both states at the same time (remember Schrödinger's cat? That's exactly such a state, except that unlike atoms, cats cannot actually be brought into such a state). More importantly, such a superposition can extend over more than one qubit, in which case each single qubit doesn't have a defined quantum state at all, but only the whole set of qubit has. This is called entanglement.

Now, why is this so useful? Well, assume you create a set of, say, 8 qubits which are all "half zero, half one". And now you perform a normal calculation on them (but with quantum operations). Then you are actually performing the calculation on all 8-bit combinations, at the same time, i.e. for all numbers between 0 and 255. This remarkable effect is called quantum parallelism.

Now, of course there's a catch: You cannot read out more than one of the results (because reading out one destroys the superposition), and which one you get is essentially random. Ok, you now may think, I can effectively make the calculation just for one randomly selected number? So this is actually a disadvantage? Well, the point is that you can not just do "classical" calculations, but you can add operations which are not possible in classical computers. For example, there are several "half zero and half one" bit states, and you can do a quantum operation to convert one of them to |0> and one of them to |1>. Therefore you can extract properties of that result which depend not on just one of the results, but on several of them. And this allows you to actually reduce the numeric complexity of certain tasks. For example, you can search an unsorted database in O(sqrt(N)) time, instead of the classical O(N) time (N being the size of the database). The most famous algorithm is of course Shor's algorithm which allows factorizing large numbers in polynomial time, thus allowing to break public key encryption systems like PGP.

Now, there's not too much danger yet, since AFAIK the biggest number successfully factorized with a quantum computer is 15. But then, as long as 5 qubits are newsworthy, you cannot expect too much (imagine a message that someone managed to build a classical 5-bit computer!).

Re:"What's a qubit?",

[swordboy]

It is the Qbert's distant cousin.

Re:"What's a qubit?",

[JohnFluxx]

Just to expand on this post, you can treat |0> and |1> as vectors. Well actually they are vectors.

So |0> is [1,0] and |1> is [0,1]

So a "superposition" is simply A*|0> + B*|1>
= [A,B]

Nothing particulary fancy or anything.

The analogy I used to explain it to my dad is this:

Imagine I have a light bulb, with a dimmer switch. I could set this to a dimmer switch to anything in between on and off. Theoritically I could store an infinite amount of information in the dimmer switch. Imagine I took a large book, converted it to hex, and turned that into one long number. Then I prepended 0. to the front.

So you get "0.1939434....". Then I set the dimmer switch to that exact value.

But, if I want to look at the light, for some reason, I can only see if it's on or off. The chance I see it as being on is the same as the dimmer switch setting. (So if it's set to 0.5, then I have a 0.5 chance of seeing it as on, and 0.5 chance of seeing it's off).
I'm stretching this analogy a bit, but you can see that despite storing anything I want, I can still only read it as on or off.

So.. how do we use this usefully? We don't really know many practical uses, but what you can do is do calculations.
Say you put two of these lights in a room. Both are set to 0.5 brightness. With the case of the lights, the total brightness is now 1. So we've gone from having probability, to something definite. You are always going to see that as being on.

The analogy doesn't quite fit, but you can see how you can use the underlying probability to do calculations and get a definite answer.

Re:"What's a qubit?",

[Unassuming Puppy]

The most famous algorithm is of course Shor's algorithm which allows factorizing large numbers in polynomial time, thus allowing to break public key encryption systems like PGP. Please explain to me something. Shor's algorithm is O(sqrt(N)) when a conventional computer would be O(N) for factorization, is it not? If so, why would PGP not be made safe again by roughly doubling the number of bits in the key, making the problem O(N^2) bigger?

Re:"What's a qubit?",

[maxwell demon]

No, the O(sqrt(N)) is for the database search problem. Shor's algorithm is O((log N)^3) if N denotes the number to factorize. So doubling the number of bits means you just have to run the algorithm 8 times as long.

Re:"What's a qubit?",

[Prowl]

somewhere in canada

Re:"What's a qubit?",

[Anonymous Coward]

From Cosby's "Bill Cosby is a very funny fellow, Right!" from 1963. I remember listening to this in the late 60's

Here's the text much funnier if you hear it though.

Re:"What's a qubit?",

[slimak]

With the case of the lights, the total brightness is now 1. So we've gone from having probability, to something definite. You are always going to see that as being on.

Maybe I don't understand the analogy...

Assuming that the light uses a dimmer switch as described in http://home.howstuffworks.com/dimmer-switch.htm/pr intable then the two lights will both be on/off at the same time (same sinusioudal source begin converted to on/off signal). So, the probably of light being on is still 1/2.

If instead, we use an old dimmer (with variable resistor), then it is simply the voltage that is adjusted and the light is on always.

If instead, we assume that light is being driven with a random (i.e. some unique source other than power signal) PWM that is high (light on) 50% of the time? If so, then the probability of _a_ light being on is 1-prob(no light on) = 1-(.5*.5)=.75 so it is not definate (and never will be unless the light state is deterministic).

Can someone adjust my thinking?

Re:"What's a qubit?",

[Suicide Clown]

Maybe you've just left out some important details for the sake of clarity, but please let me nit-pick a bit.

Suppose you write a book that converts to 0.19394...56 and I write a slightly longer book that converts to 0.1934...560000.

Whose book does 0.1934...56 correspond to?

Re:"What's a qubit?",

[gumpish]

The analogy doesn't quite fit, but you can see how you can use the underlying probability to do calculations and get a definite answer.

I can?

Re:"What's a qubit?",

[pclminion]

Your question is moot, because there's an easy workaround: use a special symbol to indicate "end of stream."

In such a system, your infinite message wouldn't even be valid, because it doesn't terminate with the "end of stream" symbol.

Problem neatly sidestepped :-)

Re:"What's a qubit?",

[rts008]

"... except that unlike atoms, cats cannot actually be brought into such a state..." Cats are made of atoms, so...***ducks,covers,and RUNS*** Sorry, couldn't help my childish self. BTW you gave a good explanation, and beat me to the punch as well!!!

Re:"What's a qubit?",

[fakeplasticusername]

Perhaps I'm revealing an intense lack of understanding, but i thought...automata theory and all...that any finite state machine could be realized on another finite state machine. Why have we not been able to build a virtual quantum computer?

Re:"What's a qubit?",

[NoOneInParticular]

Sure we can build a virtual quantum computer, how do you think the quantum algorithms have been validated? The problem is that a virtual quantum computer loses its parallel properties, so that to run an 8-bit quantum algorithm on non-quantum hardware you need 2^8 calculations per processor step. This is *slightly* prohibitive for --say-- emulating a 32-bit quantum computer.

Re:"What's a qubit?",

[div_B]

...(imagine a message that someone managed to build a classical 5-bit computer!).

If classical 5-bit computers didn't previously exist except for simulations on pen and paper we'd probably all be pretty impressed.

Re:"What's a qubit?",

[Lon]

/sigh

Bill Cosby is a Very Funny Fellow... Right! (Live)
1963

Noah sketch is track 4-6

I guess my humor references are a bit stale for the moderators today :(

Re:"What's a qubit?",

[Anonymous Coward]

Your head asplode

Re:"What's a qubit?",

[rollingrock]

Imagine I have a light bulb, with a dimmer switch. I could set this to a dimmer switch to anything in between on and off. Theoritically I could store an infinite amount of information in the dimmer switch.

Not quite. You can only store one classical bit of information per qubit. But you can "cheat" a little with entanglement and get 2.

Re:"What's a qubit?",

[maxwell demon]

Yes, cats are made of atoms, but they are macroscopic, and therefore it's practically impossible to completely isolate it from the surrounding (and BTW, if you would manage that, you'd definitely not get a half-dead cat, but a full-dead one). The interaction with the environment destroys the quantum superposition (this is called decoherence and is one of the main problems in building a quantum computer even on the atomic scale),

Re:"What's a qubit?",

[JohnFluxx]

I was kinda hoping you didn't know that a dimmer switch doesn't make the light dimmer, but rather turns it on and off rapidly.

I was thinking along the lines of using a variable resistor, like you say.
The intensity would then be at X/2 for each light. Then when you put both lights in the same room, the total would be X. (Where X is the full brightness for a given light).

I agree with what you say though. It's hard to come up with perfect analogies.

Re:"What's a qubit?",

[JohnFluxx]

You miss my point. You can view it as you store an infinite amount of information, but you cannot read it - like you say when you read it directly, you only get one classical bit of information.

First quantum OS

[Chuns]

Should the first quantum OS be M$ or Linux? :) I like to watch people argue about OS's. Makes me smile.

Re:First quantum OS

[fstrauss]

It'll be both until you boot it.

Re:First quantum OS

[R.Caley]

Does no one remember QDOS?

Re:First quantum OS

[mog007]

You havn't heard? The OS comes in a box with only a picture of a cat on it, and you won't know what OS you have until you open the box and install the software. But if you actully figure out what OS you're using it'll change for absolutely no reason.

Re:First quantum OS

[cyfer2000]

Are we still going to use mouse? Or a cat with two buttons labeled as "alive" and "dead"?

Re:First quantum OS

[Anonymous Coward]

It'll have all the windows virus, torjans and spyware problems, and Linux's lack of applications.

Re:First quantum OS

[thesandtiger]

So dual booting won't be such a pain in the ass, then. Excellent!

Re:First quantum OS

[maxwell demon]

Except that you can't control which operating system comes up: That will be completely random. If you are unlucky, you'll get the desired operating system only after a lot of boot cycles.

Re:First quantum OS

[thesandtiger]

Except that you can't control which operating system comes up: That will be completely random. If you are unlucky, you'll get the desired operating system only after a lot of boot cycles.

But since all possible boot cycles happen simultaneously, this shouldn't be a problem.

Re:First quantum OS

[R.Caley]

Does no one remember QDOS?

[modded down like a thin giraffe in quicksand]

I'll take that as a no then:-).

``I don't know, kids today, ...''

Re:First quantum OS

[pclminion]

Except that you can't control which operating system comes up: That will be completely random.

That isn't even true with real quantum particles. You can manipulate force fields in order to skew the quantum wavefunctions, making it more likely for the outcome to be one option than another.

Yes, the behavior is random in the purest mathematical sense, but just because something is random doesn't mean it's unpredictable or uncontrollable.

Suppose I had a 12-sided die, which had the number 1 on each face except for a single face, which had the number 2 on it. Clearly, the outcome of the die toss is still randomly determined, even though the number 2 is only 1/11th as likely as the number 1. If I were betting on such a die, I would certainly bet on 1.

Manipulating the potential to change the quantum wavefunction is sort of analogous to changing the shape of the die. If I squash the die so that one axis is longer than the other, and the "2" face happens to fall on the end of the long axis, then I have dramatically reduced the probability of the die ever coming up 2. (Try tossing a book in the air and see how many times it lands perfectly on its spine. Possible, but very, very unlikely.) It could happen, but perhaps only one in a million times.

Re:First quantum OS

[LordNimon]

Now that was witty. Kudos!

Re:First quantum OS

[databyss]

The mouse wheel can be labeled the probability wheel!

Scroll up to increase the probability that the left button is alive, scroll down to increase the probability that the right button is dead

Re:First quantum OS

[Anonymous Coward]

How about QNX, at least it has a Q in it.
http://www.qnx.com/

Re:First quantum OS

[rts008]

My vote is for the cat, these mice are getting out of hand. (no pun intended, I think?!?)

Re:First quantum OS

[clarkcox3]

But since all possible boot cycles happen simultaneously, this shouldn't be a problem.

At least, until you observe it; at which point, it collapses down to a single boot cycle :)

Re:First quantum OS

[Anonymous Coward]

Why not DOS? Given a 5-bit address register, 32 qubytes should be enough for anybody.

Re:First quantum OS

[betat]

I would have thought it would be just one button labeled "Alive/Dead"

Re:First quantum OS

[cyfer2000]

i am seriously thinking three designs.

the first one is two button mouse, ah... cat, sorry, and both button randomly assigned "alive" or "dead".

the second one is one button cat, like the one button mouse I am using, and randomly assigned and display "alive" or "dead"

the third one is also a one button system, there even no dispay before we click. Only after click, we will be notified the click is a "alive" click or a "dead" click.

And God said....

[GillBates0]

Let there be light, and there was "1".

Re:And God said....

[metlin]

Actually, there was uncertainty.

Upon further observation, it was known to have a probability of 1 ;)

On a serious note, this is awesome. With a 5 qubit entanglement and this, we might be able to build a primitive functional Quantum Computer, for the first time.

The team is now working to create a quantum gate in which two or more qubits of the register will interact in a controlled way.

Amazing. The beginnings of a first QC. We've memory, redundancy, processing capabilities and a lot more.

Now the only problem that remains is a suitable and reliable means of error correction - which is the biggest problem thus far in QC :-(

Re:And God said....

[julesh]

On a serious note, this is awesome. With a 5 qubit entanglement and this, we might be able to build a primitive functional Quantum Computer, for the first time.

I'm pretty sure that a "primitive functional Quantum Computer" has already been built. I recall IBM announcing that they had factored a seven bit number using QC techniques.

This seems promising because it's more likely to be scalable to higher numbers of bits than IBMs approach, from what I can tell.

Re:And God said....

[ConceptJunkie]

So, we're what 10 - 20 years away from a QC that both gives you your answer and blue screens at the same time?

I started a book on QC and it's a mind-shredding topic.

Re:And God said....

[metlin]

Well, I meant in a classical sense.

IBM's factoring operation was a very specific deed - it's not really a quantum computer as much as a customized quantum operation for a very specific task.

I meant something where you give an input, process it, store it and retrieve it -- entirely using quantum operations.

That is a challenging.

And IBM's task and this are two entirely different things, in terms of what they mean and what they've accomplished.

Re:And God said....

[metlin]

So, we're what 10 - 20 years away from a QC that both gives you your answer and blue screens at the same time?

Atleast.

I would say maybe 50. It's not enough if you can get a system to do something - you need to make it reliable and scaleable.

We're still tackling the very basic problems in QC, and have a very very long way to go. Error correction is still a very big problem.

Some people, such as Alexei Kitaev, have done some pioneering work but it's still in its infancy. A long long way to go.

Re:And God said....

[Anonymous Coward]

Reliable? Why would it need to be reliable? Look at Microsoft...

Re:And God said....

[Anonymous Coward]

Just curious, how many here believe some undercover government organization already have a functioning quantum computer? Or do we all believe the Internet has made technological discovery transparent?

Re:And God said....

[swordboy]

Let there be light, ...and there was still nothing but, hell, you could see it.

Re:And God said....

[bigtallmofo]

Now the only problem that remains is a suitable and reliable means of error correction - which is the biggest problem thus far in QC :-( The only problem? How about making practical those things they've done at great expense with huge impractical devices in a lab? How about proving that entanglement is for real and isn't just "spooky action at a distance" like Einstein originally derided it? Quantum computers are decades if not longer from reality.

Re:And God said....

[ConceptJunkie]

It's not enough if you can get a system to do something - you need to make it reliable and scaleable.


Or at least make sure it's fitted out with lots of blue LED's. ;-)

Yeah, You're absolutely right, but I wouldn't be surprised if we are underestimating the rate of progress. On the other hand, we've been 50 years away from affordable fusion power for 50 years.

Re:And God said....

[maxwell demon]

Actually, we have affordable fusion power since millions of years (ok, well, we don't, because we didn't exist that long). Indeed, the entire planet is driven by fusion power (with the exception of processes driven directly or indirectly by the heat from inside the earth, like continental drift, volcanoes, and some life forms in the deep sea).

Re:And God said....

[julesh]

I'm not sure. I know there is compelling evidence that the NSA were aware of cryptanalysis techniques years ago that have only just been discovered by cryptographers working in the public eye (see, for example, the modifications to SHA-1(?) that defeated differential cryptanalysis but were utterly inexplicable at the time they proposed them). But building a quantum computer is a larger project that would require a lot more funding than that... I suspect they (and other agencies around the world) have a project, but I doubt any of them are near completion of a useful system (which would need thousands of qbits to be of any practical use).

Re:And God said....

[maxwell demon]

Well, the nothing was now enlightened.

Re:And God said....

[maxwell demon]

Actually, there was uncertainty.

Well, there was Fear, Uncertainty and Doubt.

Uncertainty was finally implemented int he basic laws of matter, while Fear was reserved to animals (including humans) and Doubt was reserved for the humans alone.

You see, the entire creation is based on FUD.

Re:And God said....

[Anonymous Coward]

Yeah, but he said "affordable" ... nobody's bought the sun yet, we're just mooching off the guy who owns it right now ...

Re:And God said....

[psetzer]

The thing that's driving us crazy is the fact that adding more qubits is what makes a quantum computer fundamentally faster. For all intents and purposes, you can view a normal computer as a multicore 1-qubit quantum computer. That is, I have a computer that can handle a 32-bit word, so it's acting like 32 1-qubit quantum computers in parallel.

A 5-qubit quantum computer isn't really that fast. It's about 32 times faster than a comparable 5-bit computer, assuming that both can perform a similar number of instructions per second. Right now, these people have created one register on a quantum microcontroller. This is hard damn work. However, if they can get up to 32 qubits, then their computer would be about four billion times faster than mine at a comparable speed, on an appropriate problem.

This sounds damn fast, and it is. However, as I noted, this is working on an appropriate problem. Reversing a string, a typical example task that doesn't paralellize well at all, takes just as long on a quantum computer as it does on a normal computer. To add insult to this, by the time someone actually creates a 32-qubit quantum computer, normal computers will likely have outstripped it in most tasks, leaving it mainly for niche tasks like factoring huge numbers.

This isn't to disillusion anybody. Often in certain fields, people have greater expectations from some technology than is really possible. While quantum computers may not be magic, they will still be very, very fast computers for tasks which work well with them.

Re:And God said....

[Anonymous Coward]

Hope he doesn't have the extension cord plugged into his outlet and pull the plug on us.

Re:And God said....

[qcomp]

How about proving that entanglement is for real and isn't just "spooky action at a distance"

All theories that try to explain what we observe without entanglement have been disproven time and again. Bell's inequalities have been violated to 10 (or was it 50?) standard deviations and in various physical systems.
Quantum mechanics is is probably the most tested theory around, and entanglement is an integral and unavoidable part of this theory - I dont think there is particular need to "prove that it is for real"[1]. Einsteins dream of a complete, local realistic theory to describe nature is unlikely to come - nature just does not behave that way. And, frankly, I think it's much more fun that way...

[1] One "regime" of quantum mechanics that has not been much explored (and where quantum computers would come in handy) is massive multi-particle entanglement: can hundreds, thousands or millions of particle be in strongly entangled states? Theory predicts it, few doubt it, quantum computers require it, but it has not yet been demonstrated. (If that was the intent of your comment, see this as a clarification, not an objection.)

Re:And God said....

[Anonymous Coward]

--
Re-elect George W Bush... because nothing is more entertaining than an angry liberal.

You would have more people die violent deaths just for the sake of a little humour? Dubya's presidency aint a laughing matter dude.

Re:And God said....

[ConceptJunkie]

I just hope we don't suddenly get a power bill:


Dear Customer:

Please remit payment for the use of 1.75 x 10^39 kilowatt hours at $0.05.kWH for a total of 87.7 undecillion dollars by Monday, October 25, 2004. If your payment is late, the bill will be an additional $40. No stamps, please.

Thank you,

God

Re:And God said....

[ConceptJunkie]

I'd rather not have more people be slaughtered on American soil by Islamic nutjobs, which is why I'm voting for President Bush. All Kerry seems to care about is his image in France or the U.N., and maintaining our safety only if it is their whim. He wants to outsource U.S. sovereignty. I want Americans deciding what America needs to do.

Re:And God said....

[metlin]

Well said, thank you. I agree with you wholeheartedly. Not just that, Kerry is a socialist - the economy would be in tatters because he would be trying to please the unionists at the expense of the economy. I do not want the highschool debate captain, I want a leader who can do what he says and beat the crap out of the bad guys if need be.

Re:And God said....

[Zaak]

see, for example, the modifications to SHA-1(?) that defeated differential cryptanalysis but were utterly inexplicable at the time they proposed them

It may not be the instance you're thinking of, but I know that the NSA was involved in the design of DES. It's resistant against differential cryptanalysis (which was not discovered publically until 15 years after DES was published). DES is not resistant against linear cryptanalysis however, which may indicate that the NSA was not aware of the technique at that time.

TTFN

Re:And God said....

[WhiteDeath]

In other words, we will likely see a P9-Q coprocessor, or a P10 with inbuilt quantum coprocessor.

We certainly won't be seeing the P7 quantum CPU though.

Schrodinger's computer

[AchilleTalon]

Let us put a bit on in a box where it can be on or off after waiting a day, would it be on or off?

Re:Schrodinger's computer

[noselasd]

From the man himself

Re:Schrodinger's computer

[maxwell demon]

Let us put a bit on in a box where it can be on or off after waiting a day, would it be on or off?

Yes and no :-)

Re:Schrodinger's computer

[beanluc]

Yes!

Older News.

[modifried]

This was covered on New Scientist and IndiaTimes a few days ago. Their articles:

-New Scientist
-IndiaTimes

Re:Older News.

[dhalgren99]

You must be new here.
Here at /. we LUVS us some old news!

Right, Timothy? ;)

Re:Older News.

[fenimor]

Another story about the same: PhysOrg

Re:Older News.

[Anonymous Coward]

Who cares about old news though? 70 years ago was everyone dead? Because they couldn't get the news on the internet or the tv, they'd have to wait for the paper. For some reason I think they survived without instant news.

Re:Older News.

[Anonymous Coward]

But did those outlets cover it with the Register's trademark wit and condescension?

"Not to mention the fact that they can be counted - quite a useful property, when building a register."

Spooky action

[Zen Punk]

Wow...
I was just going to look for information on Quantum Computing and I thought that I might as well refresh Slashdot too...

Re:Spooky action

[firefarter]

Were you really sure the article was there when you read it?

Re:Spooky action

[johannesg]

I have that quite often: I need to find some information for my work, and that same day slashdot has an article about it. Sometimes it is almost as if Cowboy Neal himself had a camera in my office (he is probably sharing it with Scott Adams ;-) ).

...hey, it makes a great excuse to read /. during work!

Bill gates sez:

[Anonymous Coward]

"a 5 qubit register should be enough for anyone"

Re:Bill gates sez:

[maxwell demon]

And there is a world market for about five quantum computers.

Re:Bill gates sez:

[TheLink]

That depends on whether you unpack them from their boxes or not :D.

There's probably also a joke somewhere about trying to figure out whether a quantum computer is on or off.

Lord, what's a qubit?

[lottameez]

(ala bill cosby for you oldsters). Seriously though, what scale are we talking about here?

Re:Lord, what's a qubit?

[dncsky1530]

definition of qubit: The quantum computing analog to a bit. Qubits exhibit superposition. Thus, unlike normal bits, qubits can be both 1 and 0 at the same time.
thankyou NTN

Re:Lord, what's a qubit?

[wongn]

what's a qubit

I assumed that it was a quick one... Umm... perhaps not. Quantum Bit, perhaps. Just indicating that the register, despite operateing in bits, is a quantum based thing.

Re:Lord, what's a qubit?

[mikael]

One Qubit = one Caesium atom

Re:Lord, what's a qubit?

[metlin]

Very small scale.

But it's not the scale that matters, it's the fact that it has been done. The problem with any QC related operation is the inherent difficulty -- in terms of having redundancy, storage, observation and retrieval.

That's why you keep hearing these things about quantum entanglement for 5 qubits and registers and the like. It's not the scale, it's the fact that people have been able to do them.

The problem is that a lot of things are THEORETICALLY possible in QC, but have not been practically achievable. Often times, people find that although it is theoretically possible, it's not realizeable due to some problem or the other. And then, further studies would prove that there are variables that people hadn't considered.

So, this would mean that we can store observed states -- in some way that can be copied and retrieved -- which is a big leap.

Caesium

[wongn]

What is the advantage of using caesium?

Re:Caesium

[DigitumDei]

I think it has to do with this.

Dark State

Re:Caesium

[johannesg]

Caesium atoms are quite cheap, especially when you need several of them. They are just looking forward to a future scenario where they might need to invest in 10 or even 15 atoms.

Re:Caesium

[metlin]

Several reasons - it's heavy, easier to be made neutral and easier to be trapped in a wave dipole trap (that's what they seem to be using). In a standing wave dipole trap, the first factor especially plays an important role in sustaining stability.

Plus, they've a discernible signature even in a spatially modulated environment and that helps.

Re:Caesium

[Anonymous Coward]

Cesium is one of the largest atoms (electron cloud size) that lack radiological properties sufficiently incompatible with this type of work.

It's not the ideal material forever, but it's the easiest to do the initial research on.

Re:Caesium

[Anonymous Coward]

Maybe you don't care, but if you compare your link on the site which copies wikipedia content to sell ads with the actual wikipedia article, you'll notice that the wikipedia article is less cluttered and more current.

In case you aren't aware, wikipedia is a volunteer-run effort to create a free encyclopedia. Freedictionary.com is a commercial enterprise trying to make money by feeding off the efforts of wikipedia. It's sort of like Caldera in the early days, before they became SCO.

I was hoping that you had just hit upon the freedictionary.com crap by an errant search engine, and when informed of your ignorance you would be excited to learn about wikipedia, which is a much better resource for a number of reasons.

Re:Caesium

[Splab]

Strange, the words look english - but put together it makes no sence at all :)

Re:Caesium

[DigitumDei]

Okay, lets put this another way.

I use wikipedia. If I know exactly what I'm searching for, wikipedia is where I go to look. If however I sort of know (as in this case where I had read it once before and couldn't remember the term "dark state") I use Google.

When using Google, I will use the first correct link I find. In this case it was freedictionary. The information is identical to the stub in wikipedia (I just checked), so I'm not terribly worried about posting it. We can get into the moral issues here, but as I said, I was only interested in posting the information.

I'm sorry I offended you so much...

Re:Caesium

[Anonymous Coward]

Plus, they've a discernible signature even in a spatially modulated environment and that helps.

Ok Mr.Crusher, stop browsing slashdot and get back to fixing the plasma intake valve.

Re:Caesium

[Anonymous Coward]

It's not offense, I just thought you were ignorant.

I guess the problem is that the way Google works, the freedictionary link is showing up because other people are linking to freedictionary. So when you link them more, it becomes a vicious cycle. Which is exactly the intention of freedictionary's plan to dupe users into coming to their site. The problem with this is that users of freedictionary don't see the Wikipedia "edit" links and fundraising announcements.

At the "I don't mind being duped" stage I lose hope.

Re:Caesium

[hackwrench]

You know what the solution to that is...
http://en.wikipedia.org/wiki/Dark_state

Re:Caesium

[_the_bascule]

errr, a bit off topic, but, does this physical property make the building of a light-sabre a la star-wars more likely? A friend and I used to discuss building one and agreed that the problem would be stopping the laser, seems like there is a possible solution, or at least a direction. Thanks interesting info.

Re:Caesium

[Anonymous Coward]

The trick to building a lightsaber, I'm reliably informed, is to produce laser light in a form known as a Bessel beam, where the intensity basically drops to zero after a short distance.

Unfortunately the distance is of the order of a few millimeters, and the beam is only around 1 wavelength of the light (~500nm) across, but it's a start :)

Quantom Computers on the market.

[noselasd]

In other words, we won't be seeing any quantum computers "quite" yet.

Re:Quantom Computers on the market.

[Anonymous Coward]

Maybe, depends which way you look at it.

Cesium and Laser Beams

[blankman]

So in ten years I'll have to wear a lead apron and protective glasses when I turn on my new computer? New fashion trend for geeks that never shut their boxes off.

Re:Cesium and Laser Beams

[choas]

Darwin strikes again :)

Darwin: Serveral billion - Humanity: Zilch

Re:Cesium and Laser Beams

[AchilleTalon]

Caesium 133 is a stable isotope of caesium, there is no need to wear a lead apron. However, caesium is explosive in cold water and toxic. So, you rather than not install your motherboard in a plexiglas or plastic case or spilling your lemonade on your laptop.

Re:Cesium and Laser Beams

[maxwell demon]

Well, with 5 Caesium atoms, you'll not get much of an explosion. Even with 10^13 caesium atoms (which would be about a quantum-terabyte) the explosion would probably not be noticable at all. Also, in that amount the toxicity is probably negligible either.

Re:Cesium and Laser Beams

[AchilleTalon]

In the original post, the commenter is talking about an hypothetical computer, not about the experiment. So, how much ceasium will there be in this hypothetical computer? And, these days 1 Terabyte is nothing more than 1/1000th petabytes.

Re:Cesium and Laser Beams

[VoidWraith]

The issue though is that the humidity of the environment must be strictly controlled. Though this shouldn't present too much of a problem with the tiny scale (vacuum (minus the cesium), perhaps?).

Re:Cesium and Laser Beams

[maxwell demon]

I'm pretty sure the atoms have to be in vacuum (except for the atoms and the laser beam, of course). Even an inert gas would interact with the cesium atoms (not through chemical reactions, but by conventional mechanical collision and van-der-Waals interaction), and every interaction causes decoherence, that is, destruction of the quantum superposition.

Dum DUm Dum

[bigattichouse]

What they didn't know, was that (like all good sci-fi comics prior to the graphic novels of the late 80's) there was only one way to unlock the door of the secret super evil overlords of darkness... and that was a 6 qubit register!

Re:Ahhh....

[Anonymous Coward]

Basically, with an approx 2.7% error, they can switch the state of the qubit using fantastically, amazing equipment (a "laser"), then measure the new state of the qubit as a function of spin-echo time, using more fantastically, amazing equipment (a "magnet"). Then they go home.

Not quite there!

[bWareiWare.co.uk]

Whilst I am sure this is a step forward there must still be a big step between creating a 5-qubit register and a 5-qubit entangled register. With what they have created can only do the same as a five bit digital computer, with the second you could <insert you favourite quantum hyperbole here>.

Re:Not quite there!

[Anonymous Coward]

Yeah, but once they have mastered entanglement, they can break all 5-bit encryption known to man! Be very, very afraid!

Re:Not quite there!

[UnHolier than ever]

You are right, what they have done is the equivalent of creating five 1-qubit computers side by side, which is not terribly useful. It basically allows you to factorize one (factors are one and....), but FIVE TIMES!!! Still, there are first steps to everything. Let's see if they are able to do interactions.

Re:Not quite there!

[maxwell demon]

Oh shit, I really should switch to 6-bit encryption!

Re:Not quite there!

[forkazoo]

Au Contaire, Monsioueur! With the second, you could insert *everybody's* favorite quantum hyperbole, *simultanously!*

Coral cache link

[Anonymous Coward]

Coral cache link here.

Can somoene explain...

[JustNiz]

what the benefit of this approach is?
I mean we have registers already....

Re:Can somoene explain...

[qcomp]

From the theorist's perspectice it doesn't really matter how you implement this stuff - if it works, all implementations are equivalent.
But of course ther are (and will remain) technical advantages of certain implementations. I do not think that currently anybody knows what the most promising physical system is. Trapped ions are probably most advanced at the moment. Compared to them neutral atoms in optical lattices might two advantages: optical lattices appear to be rather "scalable", i.e., one might go beyond 5 qubits rather quickly, once complete coherent control has been demonstrated. (In a linear ion trap there will be difficulties to go beyond 10-20 ions, though very promising ways around these difficulties have also been demonstrated.) On the other hand, using neutral atoms (rather than charged ions) may make the qubits less susceptible to stray fields and other sources of decoherence.

At the current stage it is very reasonable to explore all possible routes to a QC (atoms, ions, photons, quantum dots, superconductors etc, a nice and readable uptodate overview is given in the Quantum Computation Roadmap): first, since it is not clear which will turn out to be most successful and second, because along the way lot of interesting physics can be expected from the coherent control of well isolated physical systems.

Re:Can somoene explain...

[metlin]

From the implementation point of view, they still face some problems.

For instance, they have used Caesium atoms to perform the storage - because it is neutral (therefore is unaffected by electric and magnetic fields), and it's an Alkali atom that can be manipulated using wave dipoles.

Great.

But Caesium _cannot_ form Bose Einstein Condensates. Therefore, you'll have problems performing quantum entanglement on such a system. Which would make it harder for us to build error correcting codes and a bunch of other things :-/

Ofcourse, people have used Rubidium to solve this problem before (w.r.t. building a BEC using an element that can also be manipulated using wave dipoles) -- but the specifications of this particular experiment do not seem to show that this is possible.

Which kinda really sucks, but I sure as hell am hoping that things get better :-)

Re:Can somoene explain...

[qcomp]

i fully agree that there are still big hurdles to overcome before any "quantum computation" is realized. However, I do not think that it matters much whether they use Cs or another Alkali. AFAIK, no BEC is needed for quantum computing: The initial state of the atoms in the lattice should be all atoms in the internal and motional ground state, and one per lattice site, i.e., not a BEC but e.g., the "Mott insulator" phase of the lattice. To start with a BEC and then inducing the Mott insulator phase transition appears to be a nice way to load the lattice, but it is not the only possiblity.
The entanglement needed for quantum computing can be achieved with Cs as with other atoms via the dipole interaction.
Don't worry, things will get better for the atomic qubits and for the solid-state qubits as well... ;-)

Re:Caesium, cheap!

[Blitzenn]

I got 5 caesium atoms free from Ron Popeil when I ordered my Showtime Rotisserie! They came in a seperate package from the steak knives. That's probably where these scientists got their's. That's why they used five atoms I suspect. To bad they didn't have money to buy the second Rotisserie and get a ten atom computer. I couldn't find a laser standing wave generator on Ron's site though. hmmmm.

38 Posts and no references to Ghostbusters, yet

[Graemee]

trapped by a laser-beam grid

For God's sake don't let the EPA turn off the grid.

Re:38 Posts and no references to Ghostbusters, yet

[maxwell demon]

So for quantum computers, an USV is much more important than for classical computers. With a classical computer, you may lose your data on power outage. With a quantum computer, you lose your computer on power outage.

Quantum register vs IBM quantum "computer" ?

[Knx]

I've to display my ignorance here, but could someone please explain in what way this is more interesting than what was achieved by IBM about 3 years ago? (See also here for Shor's algorithm.)

Re:Quantum register vs IBM quantum "computer" ?

[qcomp]

could someone please explain in what way this is more interesting than what was achieved by IBM about 3 years ago?

NMR quantum computing as demonstrated by IBM has many drawbacks.
First, there's not a single quantum system doing the computation, but rather some 10^20 molecules in the liquid - and you need so many to generate a detectable signal.
Second, the NMR quantum register cannot be properly initialized, rather it is in a nearly random state with only a slight enhancement of "0" over "1". This is part of the reason why so many systems are needed and it prevents the currently realized systmes from displaying any entanglement.
Finally, it is not clear how to scale such a system (increase the number of nuclear spins on a molecule): the larger that number, the more difficult it is to address individual qubits.

For these reasons, liquid state NMR is not be considered to be scalable. Nevertheless, the NMR people have amazing control over the operations (logic gates) they can perform, and these ideas may (and have) fed back to other implementations. Moreover, there are attempts to overcome the mentioned difficulties (while keeping some advantages of NMR) by using nuclear spins in cold solids following Kane's proposal).

Re:Quantum register vs IBM quantum "computer" ?

[Anonymous Coward]

Just a different tech really, the IBM (Issac Chaung) method uses the properties of a molecule:

5 Fluorine atoms joined together by Carbon atoms.

Where each Fluorine atom was a data storing "qubit".

There are lots of these molecules in a tank but they just store the same data, to give a larger reinforced signal than a single molecule. Hence the computer is limited to FIVE "qubits" no matter how many molecules you have.
You are limited by the complexity of the molecule.

.

The German trap would be expected to be more scalable, you can add more qubits by just (heh) making it physically "bigger" (longer).

.

Of course my field is solid state QC and it will OWN U ALL MUHAHAHAHAHAHA.... damn decoherence :(

Re:Quantum register vs IBM quantum "computer" ?

[Anonymous Coward]

Oops, SEVEN Qubits, some of the carbon atoms are used too.

Sorry. (Beaten by 3mins too)

how high can it count

[Anonymous Coward]

so now it can maybe count to 32 (or not -- you don't know 'till you measure).

Re:how high can it count

[Gizmhail]

Since qubit can have 3 states, I think that it can now count up to 3^5, ie 243 ;). No ?

Re:how high can it count

[maxwell demon]

3 states? Where did you get that?

Actually a qubit can have infinitely many states, but only two of them can be read out reliably.

Re:how high can it count

[Gizmhail]

Humm...I guess I mixed it up with qutrit. Gonna check this ;) Thx anyway to have warned me :)

From the Wikipedia: qubit, quantum cryptography

[Spy der Mann]

Qubit.

A qubit is not to be confused with a cubit, which is an ancient measure of length.

A qubit (quantum + bit; pronounced /kyoobit/ ) is a unit of quantum information. That information is described by state in a 2-level quantum mechanical system, whose two basic states are conventionally labeled |0> and |1>(pronounced: ket 0 and ket 1). A pure qubit state is a linear quantum superposition of those two states. This is significantly different from the state of a classical bit, which can only take the value 0 or 1.

A qubit's most important distinction from a classical bit, however, is not the continuous nature of the state (which can be replicated by any analog quantity), but the fact that multiple qubits can exhibit quantum entanglement. Entanglement is a nonlocal property that allows a set of qubits to express superpositions of different binary strings (01010 and 11111, for example) simultaneously. Such "quantum parallelism" is one of the keys to the potential power of quantum computation.

--------- end quote -----------

Quantum cryptography
From Wikipedia, the free encyclopedia.

Quantum cryptography currently has two aspects. The first is quantum key exchange, a method for securing communications based on quantum mechanics. The second is the conjectured effect of quantum computing on cryptanalysis, although it is currently, like quantum computing itself, only a theoretical concept.

The basic idea in quantum key exchange is to use the "noisy" properties of light to render incoherent an image that acts to complement a secret key. This image can be represented in a number of ways, but the ability to decode that image rests upon an understanding of how it was made. No way to intercept the transmission without changing it is possible, so key information can be exchanged with great confidence it has been transmitted secretly.

Using quantum superposition as a part of the computation, quantum computing will considerably extend the reach of cryptanalysis, making brute force key space searches much more effective -- if such computers ever become possible in actual practice.

----------- end quote ----------
NOTE: Please read the actual wikipedia articles. They have TONS of hyperlinks with full explanations!

Re:From the Wikipedia: qubit, quantum cryptography

[narcc]

That still doesn't explain why my cat died...

GET THE DAMN PDF.... :)

[Anonymous Coward]

This is pointless apart from proving how *purposely* complex, physics papers are.

.

I need pictures, and not raw "tex".

Damn, physics bods *mumbles*.

Uh, what I'm reading...

[nativespeaker]

We have to recalibrate the lateral baffles, and rotate the shield harmonics! Ziggy swears you should have leaped by now!

Awesome.

[Bill, Shooter of Bul]

They almost have a qubyte! Think of the power!!

Re:Awesome.

[maxwell demon]

They almost have a qubyte! Think of the power!!

Power of two, I guess?

Re:In Communist Russia...

[Anonymous Coward]

And in Capitalist America YOU register qbits. Yes?

Re:Caesium, cheap!

[Eccles]

I got 5 caesium atoms free from Ron Popeil when I ordered my Showtime Rotisserie!

It's not real caesium, though! It's qubic zirconium...

quantum random number generator

[Anonymous Coward]

All you need is one quantum bit in a cpu and you can generate genuine random numbers of any size. Sure beats psuedo random numbers.

I cannot believe it ...

[maxwell demon]

More than 100 posts, and still not:

Imagine a Beowulf cluster of those!

Re:I cannot believe it ...

[Anonymous Coward]

You can not properly imagine a beowulf cluster of those, without a... beowulf cluster of quantum computers...

Damn paradoxes...

Programming...

[Anonymous Coward]

So do you program it using QBasic?

Re:OMFG this is 1337

[genner]

Mmm...Pancakes....

QC as a PC

[like.narly]

Unfortuantely, the way scientists see it now, we'll probably never have a desktop quantum computer (or at least for a very long time). The problem is that the interaction takes place in an extremely controlled environment. Granted, the first analog computers were large, but that's because solid state wasn't really around yet. The "parts" of most QC's are acctually on the nanometer scale.

For example, one qbit setup is to use a helium superfluid, which naturally bonds electrons to the surface. The bound electrons can then be controled with a combination of microwave radiation and an electric potential from wafer posts under the fluid. Each electron (qbit) sits on top of a post, which are spaced just a few nm apart. The system is still being developed, but the nice thing is once they get it to work, they can just build a large wafer holding millions of qbits.

However, the huge problem with the above example is that it needs to run at about 50 mK, which is very close to absolute zero and requires a dilution fridge, which is a 6 foot tall cylinder. There are similar (though more complicated) limitations to the laser trapping methods.

For a commercial unit I suppose the QC wafer, microwave source, and dilution fridge could be packaged together nicely, but it is still 6 feet tall, heavy, not well suited for a house. Even if it were possible to make one small enough, there are currently no real benefits for a home user unless they really wanted to find elements in a large array or crack PGP codes... I suppose the first computers were also only suited for a lab environment and scientists probably thought the average person would never need a computer either, so who knows what will develop in the next 50 years...

Re:QC as a PC

[CMan0]

It's not completely correct, at least as far as i understand from the article, they used the very cold state to intiate the register, but then they let it heat up.

Re:QC as a PC

[bratboy]

I think there are two points to this - the first, being that we probably never thought that there'd be an atomic clock on a chip, but time marches on.

The second, and to my mind more interesting point, is that the cat is, to a certain extent, out of the bag. Especially if the basic research is being done all around the world, and made freely available. There's going to be a point in time between when house-sized (but usable) quantum computers are available to governments, and when they become ubiquitous (I can't wait to get a graphics card with quantum ray-tracing). During that time, governments will have perfect encryption and decryption, and you and I will not. Of course, I absolutely trust the (insert name of government here) and its benevolent intentions, but for you conspiracy freaks out there...

On the other hand, it kind of reminds me of a (fairly well-known?) short story about a machine that allows users to view the past - and about the government's reasons (legitimate, you discover in the end) for trying to keep it under wraps. (Does anyone remember the name of this story?) I know it's heresy to say on /., but I worry about what happens when perfect encryption becomes ubiquitous.

Re:QC as a PC

[marcosdumay]

Well, home users also need to find elements in large arry (don't need to crack PGP codes yet, I think) and this need will be as big as fast home computers can do that.
It's very problable that QC will need liquid helium (or maybe liquid nitrogen) for a long long time. But maybe they can be built small. And with little improvements, it can be very easy to keep liquid helium at home (like it is today to keep liquid hidrogen). That said, maybe people will have QC at home.

Misleading

[James Turpin]

I've taken a class in quantum computing, so I know a little bit (pardon the pun) about this.

IMNSHO, It's not really a 5-qubit register until you have interaction between the bits. That is their next step, but until then, it just doesn't count. The reason is that, other than the third "indeterminate" state that randomly returns "1" or "0" (which they also do not appear to have tested), without interaction between bits they might as well be classical bits. There is no computing advantage (other than true-random number generation) without the interaction. If they demonstrated the random-number generation capacity, I would admit that they have 5 1-qubit registers. But I won't give them credit for a 5-qubit register without demonstrating interaction between bits.

The Network is the Qomputer

[Doc Ruby]

"Qomputing" (qubit computing, get it?) is pursued independently across the globe, with separate teams reporting breakthrus in different pieces of the puzzle. One team has produced quantum entanglement, using "spooky action at a distance" to offer apparently instant communication between terminals. If each of these components in its distant lab were entangled in a quantum net, we'd get a qomputer built from the start to network in parallel while computing literally in parallel. Linux's unix heritage shows the compelling momentum derived from including networking from the beginning of the platform. Qomputing is born in the age of the network: entangled networks are natural midwives and gossips for a new qomputing qommunity.

Re:The Network is the Qomputer

[Angstroem]

"Qomputing" (qubit computing, get it?)

I guess, the first application running will be the

(drumroll)

Qonqueror.

Thank you. You're a wonderful audience.

Re:The Network is the Qomputer

[bratboy]

Sounds like Jane from Speaker for the Dead.

Re:The Network is the Qomputer

[Salsaman]

Linux's unix heritage shows the compelling momentum

Shouldn't that be "qompelling" ?

Re:The Network is the Qomputer

[Doc Ruby]

quite

Quantum Physics intro

[Zarniwoop_Editor]

Here is a link to a great video collection, sorta a quantum physics for dummies among other things...

http://www.pbs.org/wgbh/nova/elegant/ The Elegant Universe

Check it out, It's worth a visit to the Quantum Cafe.

Re:Quantum Physics intro

[BelugaParty]

I watched that series... I found it lacking. The main problem is that it introduced a lot of ideas, but didn't try to explain anything. It seemed like a chicken soup for the tired-of-the-current-foundation-of-physics soul; or an extended infomercial (take your pick). Maybe you can recommend books instead.

Re:Caesium, cheap!

[Blitzenn]

Darn! Darn! Darn! (in my best Herman Munster voice).

Re:"What's a qubit?", Just in time for ...

[davidsyes]

Oktoberfest. (For a sec, I thought Q-bert, hehehe...)

Cause to CELEBRATE!

Where can I find a Q-BIT-Love machine? All 100 or so positions and combinations at once. Rudy "The World's Greatest Lover" Valention, umm, Valentino would be jealous.

Unlike a cat, III could exist in ALL states, in all states, inexhaustibly, right? Come one, Come all, Stay awhile and have a great ball...

(OK, maybe we dont' want Cyrano D in all these states...)

Re:"What's a qubit?", Ahh, the ooolld end of

[davidsyes]

stream trick.

But:

-- will it work for taxes? (We all could use side-stepping some taxation...)

Can it solve hanging chads problems? (We need restored confidence in the voting process...)

Can we go back in time and bring back simpler life (and neatly 'sidestep' the arrival of some of history's most vile bipeds with devious, vile, obtuse, corrupt, malevolent brains? (at the citizen, local, county, municipality/parish/commonwealth/prefecture/provin ce/state, federal levels of human governance?)...)

If only such a machine could be used to alter the course of:

-greed
-excess wealth
-jealousy
-racism
-bigotry
-famine
-pe stilence
-arms dealers
-drug peddlers
-morose human spirits...

I guess God would be BORED as HELL if life were THAT nice, nice as a butterfly feeding on a plant.

"Diety Absenteesim is running rampantly high" these days. (David Syes)

Geeks don't need lead aprons

[Chemisor]

> I'll have to wear a lead apron and protective
> glasses when I turn on my new computer?

Geeks have no need to wear a lead apron, for reasons that should be obvious after a moment's reflection. And as for protective glasses, well, most of us already wear them...

What's a Qubit?

[Anonymous Coward]

When asked for comment, Qbert replied, "^%$#@!".

Entanglement

[rts008]

Imagine, desktop QC (quantum computer) that also teleports you through the network (remember: internet=Big Friggin Network!) to your favorite prOn site! Seriously, researchers in UK were teleporting photons 600 ft (or meters, can't remember) across a river between the two labs. At least I think it was in UK and photons, could be wrong on the where, but it was done. Progress seems slow now, but tech has a way of snowballing and gaining velocity very quickly. Don't count it out in our lifetime, I'm not. (I'm 46)

Not exactly...

[SuperKendall]

In ten years your computer will have known you wanted to use it and booted ten minutes ago, already displaying the google search results for what you were looking for!

Just don't open the case for a peek, or you'll literally let the cat out of the bag (or case as the case may be).

Wouldn't it be quicker...

[SuperKendall]

Wouldn't it be quicker to wander down to the NSA and borrow some time on thier 2048 bit quantum-entangled computer array?

Just thought I'd help.

Analysis & request for help

[tbo]

Disclaimer: I'm a graduate student doing research on quantum computing in optical lattices. I'm not affiliated with the group that published this article.

This result is quite exciting, because it demonstrates the feasibility of some of the techniques necessary for an optical lattice-based quantum computer. Imagine taking their 1-D lattice and turning it into a 3-D lattice, with about 30 atoms in each direction. That's a whole lot of qubits...

So what are the next steps?
1) A new means of addressing atoms (selecting one or two atoms on which to perform operations while excluding the rest) is necessary. Their magnetic gradient technique works fine for a small 1-D lattice, but it would likely be impractical for a large 3-D lattice (Maxwell's equation div B = 0 gives one major obstacle, which would require fancy tricks to overcome).
2) One and two-qubit gates need to be demonstrated using an appropriate addressing scheme.
3) Error correction, which would likely require quantum non-demolition measurements to check to see if an atom had been lost from a lattice site. Translation: we need to be able to measure if we've lost an atom from a lattice site, without disturbing the atom's state (i.e. measuring whether it's |0> or |1>).
4) Full-blown fault-tolerant computation.

My group plans to solve (1) using an addressable optical lattice. What that means is that the lattice spacing is sufficiently large that a laser can be focused on an individual atom (in 3-D, two lasers in orthogonal directions would be used). I'm currently doing simulations of one-qubit gates in this scheme.

That brings me to my question for slashdot: Some of the simulations I'll be doing (specifically, studying decoherence in the one and two qubit gates) will be very computationally intensive. They're also embarrassingly parallel, as they're essentially quantum Monte Carlo simulations. Would people be interested in a BOINC-based distributed computing project (a la SETI@home) to help develop quantum computers? If so, what kinds of things would help you get involved? Would you be interested in helping develop the software (it's C++)?

I probably won't be at that stage for another six months to a year, but it would be helpful to me to start planning now. I have just (last night) completed the core simulation engine, and would need to add code for decoherence, as well as adapt it to BOINC. The code will be GPL'd, of course.

Re:Analysis & request for help

[condensate]

I guess, as in the case with SETI@home, people could be found to do it, although it is not as sexy. I don't understand the workings of BOINC, so my question is how would you coordinate computers over the net, with a massively parallel algorithm such as quantum MC?

Re:Analysis & request for help

[808140]

Scientific progress goes BOINC?

Re:Analysis & request for help

[HoboMaster]

I'd run BOINC for that! I'd offer to help code, but I'd probably screw the whole thing up. :-P

Re:Analysis & request for help

[gnuLNX]

Hell Yes! tell me what I can do to help...

gnulnx@gmail.com

I am a computational chemist....my quantum is not really up to par, but I have been writing code since I was 12...I am now 30. I have dveloped an entire CADD program including scripting, Molecular mechanics (AMBER based). Oh and it is all C++.

I can''t promise a set amount of time, but I would certainly be interested!

Following Qomputing will be...

[neuro.slug]

The power of infinite computing power, known as iComputing. Hmmm... sounds familiar.

-- n

quantum has long been dead

[Anonymous Coward]

people that proclaim quantum computing exists are wrong. If quantum technology was available, then einstein would have known the physics required to make it real when he was understanding (not describing, but learning) nuclear physics. There will never be quantum computers because 1) the energy required to do simple things would require terawatts of power to manage the smallest quantity of information. It would not last possibly millions of years like standard designed like 8 bit nintendo circuitry and before.
2) if one person or one thing had a computer that could do what "quantum science people" claim, then it would have been devloped with the technological revolution and be a monopoly.

web: eika.tzo.com

Every time you build a quantum computer...

[hunterx11]

...God may or may not kill a kitten.