IBM Builds A Limited Quantum Computer 317 317
phr1 writes "IBM has announced and Yahoo has noted that the first working implementation of Shor's
factoring algorithm. Using NMR techniques they built a sevenqubit
quantum computer and factored the number 15 into the factors 3 and 5.
This is by far the most complicated quantum computation ever done.
It's quite an amazing featmany people thought quantum computing
was just a theoretical curiosity and Shor's algorithm could never
be implemented in practice."
if a quantum computer takes the same time (Score:2, Interesting)
Re:if a quantum computer takes the same time (Score:1, Insightful)
Tom
Re:that's not much of an upshot then... (Score:3, Insightful)
Think of a beowolf cluster of 1,000,000 athlons at 1.4ghz compared to a single 486 60mhz. The time per solution is hugely different even if the exact same binary program is used to solve the problem.
Also QC does not break any barriers related to NP != P. If a QC computer works this does not change. It just means some NP problems become faster to solve.
Tom
Re:if a quantum computer takes the same time (Score:1, Interesting)
Re:if a quantum computer takes the same time (Score:5, Interesting)
But once the molecules are put together and they can control them properly, then nothing really stops it. That is why they say that a fundamental change in cryptography is on the horizon.
Re:if a quantum computer takes the same time (Score:2, Insightful)
ironic Damn does this mean i have to use numbers greater than 5 as p,q in my implementation of RSA? Damn, even encoding my files with a 8Bit key will mean milliseconds of waiting in front of my K7. I can't stand waiting /ironic
No, to be onest i do not think the coherence length will be raised to those needed for a 256QBit QC within a decade. Until then we will use longer keys. I think that  if ever  the race Keylength vs. QC will be going on 20 years at least.
CU Seth
Re:if a quantum computer takes the same time (Score:4, Informative)
In contrast existing nonquantum techniques take O(e((log L)^(2/3)*(L)^(1/3))) time on a computer of fixed word size. To go from 4 bits to 1024 increases the run time by a factor of something like 10^18.
More to the point, on quantum computers, the race between prime finding, and so key pair generation, and factoring and so codebreaking is much less uneven.
Frightening implications (Score:3, Insightful)
It has been widely acknowledged that such agencies as the NSA have been at least a decade or more ahead of the private sector. The first govt to get a working quantum computer not only has unbreakable encryption, they are able to read any code of foreign nations. The stakes are incredible!
Soon, they will be watching all of us. Better read 1984 quickly my fellow citizens!
Re:Frightening implications (Score:3, Interesting)
2. Most meaningful research comes from the private sector (bell labs and the like) with a few exceptions (Darpa)
3. Even if the government had quantum computer level encription it couldn't get it's self organized enough to use it for more then maybe presidential level communication.
Re:Frightening implications (Score:2, Interesting)
The NSA's budget is classified. They recruit top people in research fields (and not only U.S. citizens). The estimate I've heard is that they are more like TWENTY years ahead of civilian cryptographers. Don't be fooled by the government's outward appearance of being inept. They do get things done in certain areas where it counts.
Re:Frightening implications (Score:2, Informative)
Most meaningful reasearch, by any standard you care to name (dollars spent, papers written, patents granted, etc), comes from Universities. In the US, almost all industrial basic research (IBM being a notable exception) has been eliminated in the names of quarterly profits. The problem is that the return on basic research doesn't arrive for 510 years and most companies don't look beyond next quarters balance sheet.
And, since you brought it up, Bell Labs no longer exists. When AT&T split itself up, the old Bell Labs became Lucent Corporation. The research parts of Lucent pretty much ceased to exist as of the recent restructuring where research was split up between Lucent, Agere, and Avaya.
And, as someone else pointed out, DARPA is only for the U.S. military and is a primarily funding agency, not a research lab. U.S. civilian research is funded largely by DOE, NSF, and NIH.
JS
Nonsense! (Score:2, Funny)
Re:Frightening implications (Score:5, Informative)
While I have also often heard stories of the NSA having much more advanced equipment and techniques than the private sector, or at least than the nonclassified private sector, in the case of quantum computing this is unlikely. First, it's a relatively new subject. Shore's algorithm, for example, was only discovered in the 80's. There really hasn't been enough time for them to get so far ahead. Second, the NSA is full mostly of mathematicians and computer scientsts, not physicists, so they really don't have the right staff for that. Third, most of the academic research is funded by the NSA.
Finally, though it's hard to say exactly how far this technology is from being useful (or alternately the probability that it will EVER be useful), it is probably safe to say it will be quite a while from now. Moreover, it is probably also safe to say that it only gets harder from here. Larger computations will involve the same problems as these only on larger scales plus a whole new, tougher, slew of problems that these avoid. These are chiefly quantum decoherence and entangling large numbers of quantum states.
Quantum decoherence is the loss of the special quantum information (quantum phase relations) that allows quantum computers to do their funky magic. This happens over time in any system that has any interaction with the outside world. I think these small calculations largely avoid this problem because they are reasonably fast. Larger ones involve more steps and thus will run up against these problems. Some error correcting quantum codes have been developed, but these involve even more qubits, which exaserbates the other problems, and are still largely in the formative stages.
The other big hurdle is entangling much larger numbers of particles in one state. These take advantage of the interactions between different nuclei in the same molecule. Once you need many more qubits, you will need to come up with a more general scheme for entangling the quantum states, because it's unlikely that you'll be able to engineer a molicule for the purpose. Also, the bigger you make your system, the more strongly it interacts with the outside world and the worse decoherence becomes....Life's a bitch, ain't it?
So, I think this is really exciting and quantum computers have great promise, but I don't expect to have a quantum coprocessor in my PC any time soon, nor do I really think it's likely that the NSA has a quantum supercomputer sitting in the back room decrypting my credit card information.
Re:Frightening implications (Score:2, Informative)
Re:Frightening implications (Score:2)
sPh
Re:Frightening implications (Score:3, Insightful)
Certainly. On the other hand, if you had looked at the thermionicvalve computers of the 1940's, it would have been hard to imagine the Atari 2600, much less a Beowulf cluster of quadXeons.
nor do I really think it's likely that the NSA has a quantum supercomputer sitting in the back room decrypting my credit card information.
Nor should you. However, given the way the NSA has largely backed off any serious efforts to outlaw publickey cryptography, it is likely that they have either the brute force computing power or classified algorithms to crack it, so it's not necessary to imagine exotic computing technology. Besides, if an agency like the NSA really wants information from you badly enough, you'll end up giving it to them, Winston.
Shouldn't there be a +1 Deeply Paranoid moderation option?
Re:Frightening implications (Score:2)
I think it is more probable that they realized it is much easier to attack the passphrase or find some other way of breaking into the computer, install a keystroke logger and so on, than try to decipher a message by brute force.
Or it could just be that somebody actually realized that a country where strong cryptography is readily available to everyone is actually safer for everyone.
Re:Frightening implications (Score:2, Interesting)
Schneier's Applied Cryptography has a discussion of this with regard to DES. Here's my description of it (I'm doing this off the top of my head, and I'm not an expert, so please excuse any mistakes):
In the early 1970s, IBM was contracted by the US Government to create a standard encryption algorithm that companies could use to secure their communications.
IBM was given free reign to design what they wanted, with one exception: Any algorithm that they developed would have to be given to the government (NSA) to look at, and the government would have final approval. So, after some work, IBM came up with the algorithm that we now know as DES, although what they came up with is slightly different than what is in use today...
The important part of DES, the part that does the actual encrypting, is a part of the algorithm where the incoming bits are mixed. The actual mixing can be described as a matrix of numbers. The makeup of this matrix is important, as it determines whether the bits are properly encrypted. If this block of numbers has the wrong configuration, then the numbers may not be mixed in a truly secure manner.
The question then, of course, is how to determine whether a block of numbers is "secure" or not. IBM had developed a test that would check this particular property, came up with a set of numbers that they had decided would make the algorithm properly secure, and gave it all to the NSA to check.
The NSA approved the algorithm, but with one exception: They supplied a new set of numbers for the mixing block! IBM checked these new numbers, found that they satisfied their requirements for security, and, so, that is what we are using today.
So What? About 10 years later a new method of attacking ciphers was developed, called Differential Analysis. This method was brand new, nobody had ever heard about it before, and turned out to be very powerful. Of course, DES was checked to see how secure it was against this new attack, and it turns out that the security of DES depends entirely on what numbers are picked for the mixing block.
Here's the interesting part: It turns out that the numbers used in DES, the ones that the NSA itself had generated and given to IBM, were in the 2% worst of all possible blocks to be used!
Coincidence? Perhaps...although it does seem to indicate that the NSA was aware of Differential Analysis many years before the rest of the world was, and purposely sabotaged DES to make it easier to crack. Remember that the NSA is the world's largest employer of mathematicians!
You're exactly right and wrong! (Score:5, Interesting)
But you're wrong in the fact that DES IS resistant to DC. The bit Sbox design the NSA gave IBM are designed to make it STRONGER against DC NOT weaker.
"As in choosing the key length , another of the NSA'a design criteria was based on making the algorithm [DES] resistant to differential cryptanalysis..." _AC_ first edition Schneier page 238
If you want to bust the NSA's chops complain that they made the key length go from 128 to (effectively) 56 bits. Now that hurt...
=tkk
Re:You're exactly right and wrong! (Score:2)
DES is NOT a group (proved 1992), the number of permutations (16) also makes it hardened against DiffCrypt where 8 is not enough. It wasn't until difcrypt came along that the need for 16 perms was finally revealed. (More proof that the NSA knew about DC then if we needed it.)
The permutations are also needed against linear crypt  8 permutations are 2^21 plaintext breakable and 16 is 2^43. You're right  linear is the most effective (as far as we know
The shift from a theoritical 2^47 to a real life 2^43 isn't THAT bad  seems to be a good general compromise between being hardened against a broad range of attacks. If the NSA had allowed uniform Sboxes the difficulty would fall as low as 2^26.
I do wonder in coming years if we'll learn of an NSA technique against DES we never thought of... but I have to think that if they assumed that foreign govs knew (or would come to know what the NSA knew  remember the Russian are very good at math and codes) that they really did want an allaround secure algorithm.
As I heard someone once suggest though  given that the NSA measures it's computing power in "acres" and has for years... what if they just dedicated older super computers to brute force attacks like searching for, factoring and cataloging very large prime numbers and mapping/cataloging every possible textblock in to output out of every major alogrithm? Couldn't they have an amazing precomputed brute force hammer to apply when needed? If you think your RSA is safe because of the difficulty involved in factoring very large primes  what if someone had been working on it for 30+ years with ever increasing computer power?
=tkk
Re:Frightening implications (Score:2)
IBM is no ordinary corporation  it's practically a country in its own right. Remember that two of the largest revolutions in computing (desktop PCs and relational databases) were things that IBM created, then couldn't exploit commercially, and they not only survived but thrived after two disasters like that. If anyone can do it, Intergalactic Battle Machines can...
Re:Frightening implications (Score:4, Insightful)
The core question is: Can a real, working quantum computer be built in secrecy?
IMHO, it is very unlikely. It has to do with how science works. A few things can pop out straight from a brilliant idea, and can be implemented based on that idea alone. This is, however, very, very uncommon. Even the most brilliant minds needs feedback from their peers to get anywhere. You need critisism, even strong opposition, to finetune your ideas and your arguments. This is what the greater scientific community provides.
In closed projects, even if you hire the best minds, you'll get inbreed, you will not get the same level of critisism, and soon you will most probably paint yourself into a corner.
So, while there are examples of projects that have been developed in secrecy that actually work well, most real science has to be done in the open.
Arguably, the most advanced project that we know of that was conducted in secrecy is the Manhattan project. However, building a nuclear bomb wasn't really that difficult. All the basic science was well understood in 1941, it was just engineering left. The brilliant minds found it rather boring. It was completed, and it was kept secret because of the war, there existed very strong reasons for the people who developed it to keep it secret. Hardly any such reasons exist today. A quantum computer will be so important to science and technology, I don't think you can have a larger group of brilliant minds keep it secret for very long. They would want to have the advancement of science going, and beside, they want the nobel prize.
I'm not really frightened. I'd really like to see quantum computers. Yeah, it will make PKI as we know it obsolote, and it really needs adressing fast. I'm not aware of any algoritms that can make reasonably strong encryption on a classical computer that can withstand an attack from a quantum computer, but we'll need that to be reasonably safe while we're waiting for quantum computers to be widespread enough for everybody to use. Anybody know of efforts in this regard?
Re:Frightening implications (Score:3, Interesting)
Re:Frightening implications (Score:2)
Their visible* track records over the last decade show my bet is likley to win.
* Many things both entities have done are not a part of my knowledge as that is what they wish  atleast I assume I don't know everything.
Re:Frightening implications (Score:2)
They seem to have changed their tune a bit lately, what with the Crypto Musuem, releasing a Linux distro, and generally being more citizenfriendly. But my friends who went to work there in the 1980s (some of them _very_ smart guys) never reappeared in public, so who knows what really goes on behind closed doors?
sPh
Almost There (Score:1)
Re:Almost There (Score:2, Insightful)
similar has been done before (Score:3, Interesting)
Los Alamos and "federal researchers" (Score:3, Informative)
But in March of 2000, a group claimed to have built a 7qubit quantum computer. It's based on some different techniques than previously used, but the researcher said that the techniques can't go past 15 qubits. Check it out at:
http://www.wired.com/news/technology/0,1282,351
Uh (Score:2)
Btw, the limit of 1/x as x approaches zero is infinity. but 1/x isn't infinity. If it were you could do things like
1/x = inf
2/x = inf
so 1 == 2
Re:Uh (Score:2, Insightful)
so by your logic, we can just let x go to infinity, then:
1*x = inf
2*x = inf
=>
1 = 2
of course, your conclusion is right, but your logic is wrong. that's because infinity is not a number, but rather the concept of unboundedness. (it's obvious that two unbounded quantities do not have to be equal to each other.)
Um, you disproved yourself :P (Score:2)
1.a: A specified or indefinite number or amount.
Is infinity not an indefinite number?
OS (Score:3, Funny)
I'm thinking of calling my company "Quantumsoft"
And my software would be able to slow the quantum computer to a crawl!
Re:OS (Score:2, Funny)
Write your own? Who the hell would do that? Just buy someone else's, slap your label on it, and then start bundling everything under the sun along with it.
So you want 1,000 copies of the Quantumsoft Ion OS? OK, we'll give you a great deal if you also buy 1,000 copies of Quantumsoft Cubix office suite and 1,000 copies of Quantumsoft Visual Q++.
Sounds dangerous... (Score:2)
Re:Sounds dangerous... (Score:2)
Could quantum computing ever become general purpos (Score:2, Insightful)
If they had to handcraft a molecule to factor the number 15, it would seem that quantum computing would have to be very specialized. Do they have any schemes for creating a general purpose quantum CPU?
Re:Could quantum computing ever become general pur (Score:3, Insightful)
still a long way to go... (Score:4, Insightful)
Oh, I see (Score:2)
Re:still a long way to go... (Score:2)
On a weblog that frequented by mainly computer scientists, it is..
anyone got a patch... (Score:3, Funny)
Re:Fine. (Score:2)
Need I go on?
Re:Fine. (Score:2)
but... (Score:1, Funny)
IBM's largest computer ever (Score:4, Funny)
"Previously the largest computer IBM had built was based on five atoms."
So what about the 2 ton behemoths everyone's been buying for years?
Re:IBM's largest computer ever (Score:5, Funny)
Re:IBM's largest computer ever (Score:3, Funny)
An Introduction... (Score:5, Informative)
An Introduction to to Quantum Computing for NonPhysicists [lanl.gov]  Available in PDF, PostScript, and others.
If you do a google search, you probably can find it elsewhere, also.
GFish4
Crud! (Score:5, Funny)
Damn the relentless progress of computing!
Re:Crud! (Score:2)
The standard cryptographic solution to this kind of problem is to double your key length.

Fool! (Score:3, Funny)
My boss says ... (Score:3, Funny)
have saved a lot of money."
Question (Score:2, Interesting)
I am guessing it would only be those which use factoring large numbers as their "hard" problem. Right? Obviously RSA style public key based encryption is in danger, but that just means I need to find a secure channel to exchange keys.
What implications does this have for things like IDEA or even Xoring with a big chunk of random data?
Re:Question (Score:2)
It probably suffers from the same problems.
or even Xoring with a big chunk of random data?
This is known as a onetime pad (where the key is the same length as the message), and it's unbreakable (not just hard to break). Of course, it's also difficult to exchange these keys.
Unfortunately NMR quantum computing has limits (Score:4, Insightful)
Of course almost all current quantum computing schemes have fatal flaws and NMR is well ahead of everyone else (with the possible exception of ion trapping). However in most other schemes the flaws aren't fundamental (just really, really, difficult to fix).
Disclosure: I have worked on a competing quantum computing scheme (neutral atoms). It's crap too.
Re:Unfortunately NMR quantum computing has limits (Score:4, Informative)
NMR vs. MRI (Score:2, Interesting)
Meow (Score:5, Funny)
Another article at News.com (Score:4, Informative)
You Heard It Here First... (Score:5, Insightful)
Re:You Heard It Here First... (Score:4, Funny)
because I'm not looking forward to calling it cybrpnk's law
Re:You Heard It Here First... (Score:2)
7 qbits factors 15 to 3 and 5
How many do we need to factor a 50 digit number?
How many to do some maths we just don't have time to do with Binary?
Almost there! (Score:5, Funny)
7 Qbits already? That's great! No one should ever need more than 640 Qbits.
Re:Almost there! (Score:2)
According to cybrpnk's law [slashdot.org] we should hit 640 Qbits in just under 10 years!

The End of Asymmetric Key Distribution (Score:3)
At JPL, among, there is a group working on quantum key distribution. The aim is to have entanged photons distributed at the same rate (or almost the same rate) as the data, and to use this as a crypto key that is totally unbreakable. Untappable, unbreakable, impervious.
Doesn't it strike anyone as strange and cool that quantum computers and quantum key distribution are coming to fruition at almost exactly the same time?
muerte
not true (Score:3, Informative)
Re:not true (Score:2, Informative)
Re:not in general (Score:3, Informative)
For GENERAL brute force search type problems
the speedup is as I described. See the articles
at qubit.org for more info.
Re:not in general (Score:2)
Re:not in general (Score:2)
Actually it is true (Score:2, Informative)
Granted I am not a security/encrytion expert, so your statement about this only being effective for assymetric encrytion schemes may be correct if conventially encryption is not based on a hard key, but I thought that all encryption was based on hard keys (BTW, isn't cryptography the creation of a code to hide/diguise the data, as opposed to encrypting it with a function?).
With regard to "clock" speed (There is no fundamental reason a QC needs to be clocked, but for the sake of simplicity let's say it is), NMR states are, I think, stable on the order of milliseconds, so maybe the computer could "clock" several hundred computations per second. It would still take awhile to do several million comps, or about how many comps will be required to factor something on the order of 10^25 with Shor's algorithm, but timewise that's on the order of months, not the known age of the universe like it would be for a regular computer (figures are from memory, and are meant to illustrate the orders of magnitude involved, not necessarily be completely accurate).
Granted this is all a guesstimate, but I think a pretty conservative one.
Someone else quoted rate of ~ O(10^3) computations before decoherence. A QC is probablistic, which means that you run it over and over under an interation produces the correct result. The chance of getting an incorrect answer decreases with each iteration. Shor's algorithm takes either 3 or 4 computations (defined in a QC as a evolution of the wave state) per iteration. I may be a little off here, it's been awhile, but it's definitely around that so if that quote is acurrate, decoherence is no problem, at least for the quoted setup. It also, assuming a decoherence time on the order of ms, appears to be faster than my above guess.
Essentially, even if QC's can't crack various keys in realtime, they could make key generation/distribution a real pain in the ass and essentially end the era of uncrackable encryption (unless of course it is quantum encryption which is in theory uncrackable, but I know alot less about that)
Does anyone have any data on how many comps/sec various qubit models can handle? I'd like to see if my guess was close:)
Quantum computers mean double symmetric key length (Score:2)
Namely, Grover's algorithm would enable you to brute force a symmetric key of size N in O(exp(N/2)) time rather than the current O(exp(N)) time.
In other words, if quantum computers (even with very large number of qubits) are built, today's public key cryptosystems would no longer be secure, but today's symmetric cyphers would simply need to have their key length doubled to keep the same rough level of security.
Re:The End of Asymmetric Key Distribution (Score:2)
And how exactly is it that quantum key distribution is supposed to protect us from the classic and proven maninthemiddle attack?
Re:The End of Asymmetric Key Distribution (Score:3)
Quantum encryption, when used correctly, is really truly mathematically proven to be unbreakable by any means.
Re:The End of Asymmetric Key Distribution (Score:2)
I suggest checking the literature a little more closely. A man in the middle will not disrupt the transmission, because a man in the middle is not an eavesdropper, he's pretending to be both ends of the link at once. Person A tries to communicate with person B, and establishes a secure link, but really, the secure uncrackable link is with person C standing in the middle, and person C then establishes a secure uncrackable link with person B. The problem then becomes, how does person A know that it's REALLY person B that a secure communication has been established with, and vice versa.
Preventing a maninthemiddle attack requires authentication, not secure communication. And when it comes down to it, encryption without authentication is almost useless, because maninthemiddle attacks are not really that difficult to pull off. Classically, authentication is typically done with the existence of some sort of oneway hash function. I don't know if any hash functions are going to survive the dawn of the quantum computing age.
Re:The End of Asymmetric Key Distribution (Score:3, Funny)
When you factor your first prime, I recommend publishing the result...
Old news (Score:5, Funny)
Re:Old news (Score:2)
Perhaps he brought in 7 of each sex of each animal. Then he found the one of each sex of each animal that could do the most amusing trick, and took that one into the Ark.
What this really means (Score:2)
I dearly love SSH, but if it's based on inherently transparent (to quantum computers) mathematics, it's worthless  perhaps worse, since I trust it.
We need to begin considering this problem NOW, before the privacy of just about everybody is opened up to the whim of somebody with enough money to buy a quantum computer!
There will definitely be, as Quantum computing hits mainstream in the next 515 years, a coexistence period  like twilight, the period of greatest danger, when the world of computing is based neither entirely on binary or quantum systems  and we're heading for that with momumental speed.
Stockpiling emails (Score:2, Insightful)
Unfortunately, that means people using factoringbased keys are in trouble today, because an adversary with a sufficiently large budget (and sufficent access to certain routers) could stockpile a rather large portion of Internet traffic for cracking at such time that it becomes feasible to do so.
Evidence and paranoia leads one to suspect certain parties do evesdrop on a certain fraction of email, particularly email sent across international cables. If such email is already being filtered for certain keywords, how much harder is it to filter it for apparently encrypted email and shelve it for later use?
Re:Stockpiling emails (Score:2)
Very impressive (Score:2)
A friend of mine there says their employee evaluation system has three ratings: "OK", "Not OK", and "Nobel Prize". He's only partly kidding; they have several Nobel laureates on staff.
Hacker at heart (Score:2)
IBM announcement  in history section:
"But in 1994, Peter Shor of AT&T Research described a specific quantum algorithm for factoring large numbers exponentially faster than conventional computers  fast enough to defeat the security of many publickey cryptosystems. The potential of Shor's algorithm stimulated many scientists to work toward realizing the quantum computers' potential. Significant progress has been made in recent years by numerous research groups around the world."
Maybe Magic Lantern isn't needed, and maybe the feds should be more concerned about quantum scientist as the next great public threat? Lets' see now... Hacker used to be a positive connotation.....how to turn Quantum into a negitive connotation...or is ther another name by which these scientists go by?
Super Quantum Computer (Score:2)
given that a quantum computer could factorise a number N into factors a1, a2, a3,...etc in a defined time, we can therefore tell whether N is prime by seeing if it returns a1=1, a2=N.
Would it be possible to build a 'super' quantum computer which checks simultaneously all numbers from 0 > 2^n (where n is the number of qbits) and returns only those which are prime.
In other words, you would be carrying out 2^n computations simultaneously, each of which is comprised of 2^n computations ?
Achtung! Halt! (Score:2)
[grammarnazi]
Apparently, phr1 does not need to use.
Complete sentences. =P
Either that or get rid of the "that".
[clicks jackboots,
Kasreyn
Robert Pike on qc: (Score:2)
http://www.technetcast.com/tnc_play_stream.html?st ream_id=310 [technetcast.com]
Check the slides too at:
http://cm.belllabs.com/who/rob/qcintro.pdf [belllabs.com]
Regards,
Marc
Re:Just wait until it gets more complex (Score:1)
Re:XP (Score:1)
Who exactly thought this?
Me. It's about time I got some recognition!
Re:Flame war (Score:2)
Re:explain (Score:2, Informative)
Start here: http://www.qubit.org/
Re:Someones gotta say it! (Score:2)
However, if and when this takes off, there'll be a sweet spot where it is easier to build the extra weaker computers than the more powerful larger one. Ie, $20 for a 7 qubit processor but $50 for one with 8 qubits; you'd be better off with the weaker ones.
Re:Someones gotta say it! (Score:2)
Re:Someones gotta say it! (Score:2)
I even have a dual celeron under my desk as it was (and continues to be) cheaper than a Sparc or Alpha (and many others) but is (for what I do with it) close enough is speed to the other that I don't notice.
Uhm... (Score:2)
Re:Downsides.... (Score:4, Informative)
If we don't get a more secure encryption system out before the real quantum big guns come out, ecommerce etc is basically stuffed.
Re:Downsides.... (Score:2)
Re:That's easy! (Score:2)
And maybe you're not.
Re:That's easy! (Score:2)
Too bad really. Having the answers to all the questions and not being able to share.
Re:factors (Score:2, Informative)
is based upon the fact that it is very easy to randomly pick some prime numbers and multiply them together to get an answer. The number that is produced can only be produced by multiplication of those two numbers, so there is only one pair of numbers that can be deduced by factorisation. Now, there is no easy way to determine the factors of a number, the only way is to use a brute force approach. That takes time, due to the large amount of time needed, it makes this ideal for implementation in a cryptographic system, and guess what? That's what most public key systems use. So it makes it possible for somebody to totally undermine all the existing ecommerce infrastructure and grep all of your passwords and credit card numbers and alQueda arms shipments.