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New Quantum Computing Record Set By Recycled Photons

Soulskill posted about 2 years ago | from the still-working-on-the-reducing-and-reusing dept.

Science 47

CelestialScience writes "A recycling technique has enabled a quantum computer to carry out a quantum calculation known as Shor's algorithm on a larger number than ever before. The benchmark algorithm exploits quantum mechanics to simplify the factorization of numbers into their prime components — a hard task for classical computers when the numbers get large. Until now, the largest number factorized using Shor's algorithm was 15. Now Anthony Laing at the University of Bristol, UK and colleagues report in Nature Photonics that they used a recycled photon to factorize 21 — still far too small and trivial to spook cryptographers, who rely on the difficulty of factorizing large numbers for their widely-used techniques. But a record nonetheless."

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7*3 (3, Funny)

Anonymous Coward | about 2 years ago | (#41745849)

7*3. Nailed it!

Re:7*3 (1)

History's Coming To (1059484) | about 2 years ago | (#41746121)

Not quite.

3*2 nope 5*5 nope 3*9 nope 2*4 nope 9*1 nope 7*3 nailed it 6*4 nope 2*9 nope 3*6 nope

...is closer to the truth. I need a superpositioned font to do it justice, but hey...

Re:7*3 (1)

tehcyder (746570) | about 2 years ago | (#41750167)

Duh, what about 10 1/2 * 2 then? Eh?

Re:7*3 (1)

RaceProUK (1137575) | about 2 years ago | (#41750501)

*expects a whoosh after*

Factors are always integers :P

Re:7*3 (0)

Anonymous Coward | about 2 years ago | (#41750821)

Hmmm ... I get 3*7. Must have done something wrong, I guess.

Recycled photons? (5, Funny)

Anonymous Coward | about 2 years ago | (#41745855)

Seen this before.

No danger for crypto (1)

gweihir (88907) | about 2 years ago | (#41745873)

This stuff scales incredibly bad with time. Not even a hint of a "Moore's law" here. By now I doubt they will be able to factor 1000 before the end of the decade.

1001 (0)

Anonymous Coward | about 2 years ago | (#41745899)

1001 is a much nicer number to factor anyway

Re:No danger for crypto (1)

geekoid (135745) | about 2 years ago | (#41745965)

Moore's law wasn't applicable at the beginning of transistor on wafer creation. once tools where in place, then it started to run it's course.

Re:No danger for crypto (1)

gweihir (88907) | about 2 years ago | (#41746043)

The effort invested in the first transistors and in this do not compare at all. Transistors were initially though to be useless. Turned out to be fantastically wrong. The converse is true for quantum computing.

Re:No danger for crypto (1)

Chris Burke (6130) | about 2 years ago | (#41746201)

First, bullshit, the people who actively developed working transistor devices -- specifically Bell Labs -- knew damn well that they were useful as a replacement for vacuum tubes. Maybe you're thinking of lasers?

Second, regardless of the initial R&D development effort, the Moore's observation didn't apply until after the transistor left the lab and was in full modern production and so, if it ever is, will it be with quantum computers.

Complaining about the lack of exponential growth now is just ridiculous.

Re:No danger for crypto (1)

gweihir (88907) | about 2 years ago | (#41756293)

You are thinking of bipolar transistors. FETs were known a lot longer and are what makes modern electronics tick.

Re:No danger for crypto (1)

khallow (566160) | about 2 years ago | (#41746379)

Transisters were a big step in the transition from unreliable and bulky vacuum tubes to integrated circuits. I would say that Moore's law was already in gear by the time of their development.

As I see it, the dynamic of Moore's Law was threefold. First, it provided a simple model of how fast one should be developing integrated circuit technology. Second, there were plenty of zeros to run out Moore's Law for decades because as Feynman noted, "there's a lot of room at the bottom." And third, Moore's law superficially described an R&D cycle that used previously developed technologies to develop the next level of technologies. This repetitive technology bootstrapping process is unique in our history, though we may see future such bootstrap cycles from other approaches.

Re:No danger for crypto (1)

Anonymous Coward | about 2 years ago | (#41749097)

Transister? Is that a brother who became a sister?

Re:No danger for crypto (1)

RaceProUK (1137575) | about 2 years ago | (#41750505)

No, that's a broster.

Re:No danger for crypto (1)

mcgrew (92797) | about 2 years ago | (#41752483)

Transistors were initially though to be useless.

Interesting, I hadn't heard that before, and I've been tinkering with electronics for over 45 years and have read hundreds of book about it. I looked up in Wikipedia (quoted below) and found no such indication. Do you have a link? As I said, I found that intersting and would like to know more.

The thermionic triode, a vacuum tube invented in 1907, propelled the electronics age forward, enabling amplified radio technology and long-distance telephony. The triode, however, was a fragile device that consumed a lot of power. Physicist Julius Edgar Lilienfeld filed a patent for a field-effect transistor (FET) in Canada in 1925, which was intended to be a solid-state replacement for the triode.[1][2] Lilienfeld also filed identical patents in the United States in 1926[3] and 1928.[4][5] However, Lilienfeld did not publish any research articles about his devices nor did his patents cite any specific examples of a working prototype. Since the production of high-quality semiconductor materials was still decades away, Lilienfeld's solid-state amplifier ideas would not have found practical use in the 1920s and 1930s, even if such a device were built.[6] In 1934, German inventor Oskar Heil patented a similar device.[7]

From November 17, 1947 to December 23, 1947, John Bardeen and Walter Brattain at AT&T's Bell Labs in the United States, performed experiments and observed that when two gold point contacts were applied to a crystal of germanium, a signal was produced with the output power greater than the input.[8] Solid State Physics Group leader William Shockley saw the potential in this, and over the next few months worked to greatly expand the knowledge of semiconductors. The term transistor was coined by John R. Pierce as a portmanteau of the term "transfer resistor".

Re:No danger for crypto (1)

Chris Burke (6130) | about 2 years ago | (#41753565)

As I said, I found that intersting and would like to know more.

Here's more: They made that up as a shoddy explanation for why exponential growth didn't hit transistor-based ICs immediately to fallaciously justify their irrational expectation that quantum computers should immediately experience exponential growth. Every step of the logical chain is wrong even if you assume the previous step was correct, and the starting fact was a lie.

And now you know the whole story.

Re:No danger for crypto (3, Interesting)

Anonymous Coward | about 2 years ago | (#41745997)

Even if it were more advanced now, it still wouldn't be much of a danger to cryptography.
There are enough encryption algorithms where quantum computing is not a danger.
Sure, algos using the dlog or factorisation problem would fall instantly, but something like McEliece would finally thrive.

Re:No danger for crypto (0)

Anonymous Coward | about 2 years ago | (#41746309)

Yes, perhaps! But by the end of the next decade they'll be able to factor 1763! A decade after that, they'll have hit 2319! Give it a few hundred thousand years, and they'll be factoring numbers in the HUNDREDS of thousands range. What then, with your fancy crypto... cryptomania?! What then I tell you?!

Re:No danger for crypto (1)

TsuruchiBrian (2731979) | about 2 years ago | (#41747639)

You sound like the techies on the internet in the 90s that laughed at the idea that we'd EVER have gigabytes of RAM in a single computer, let alone a few years later.

Re:No danger for crypto (1)

jovius (974690) | about 2 years ago | (#41748805)

Quantum computing is a new and unexplored field of cats, so I'd say that the cat images count too.

Re:No danger for crypto (2)

hweimer (709734) | about 2 years ago | (#41749327)

This stuff scales incredibly bad with time. Not even a hint of a "Moore's law" here.

There is. [quantenblog.net]

Re:No danger for crypto (1)

MozeeToby (1163751) | about 2 years ago | (#41753837)

The thing with Moore's law, it's a doubling time. If the number you're doubling is very, very small doubling every 6 years (which is the actual doubling time for quantum computing so far) is not going to sound very impressive. But, if we have 5 qbits today, by the end of the decade we should have around 15 by the end of the decade and be able to factor numbers in the low tens of thousands. 12 years after that and you can factor numbers in the quadrillions. 12 years after that and you can factor numbers in the range of 10^72.

Do we really need to recycle photons? (4, Funny)

BitterOak (537666) | about 2 years ago | (#41745903)

Are photons that expensive that they need to be recycled? I can understand aluminum cans, but photons are taking it a bit far, I think.

Re:Do we really need to recycle photons? (0)

Anonymous Coward | about 2 years ago | (#41746045)

It's all about the 3 R's - Reading, Riting, Rithmetic. Or was it Reduce Reuse Recycle.

Re:Do we really need to recycle photons? (1)

oodaloop (1229816) | about 2 years ago | (#41746113)

Reading, writing, and refilling our oceans.

Re:Do we really need to recycle photons? (1)

mapsjanhere (1130359) | about 2 years ago | (#41746193)

For each photon recycled you get a one electron credit on your electric bill.

Re:Do we really need to recycle photons? (1)

sconeu (64226) | about 2 years ago | (#41746313)

It's good for the photon, it's good for the quantum computer.

Re:Do we really need to recycle photons? (1)

Anonymous Coward | about 2 years ago | (#41747797)

As best I can guess from reading the article, the issue is that it is difficult to isolate the photon so that it can be used in the experiment. If they did not recycle it, they'd have to capture more. By running the experiments in series with one photon rather than in parallel with multiple photons, they make the experiment take longer to complete but leave it easier to perform. This allows them to investigate qubit intensive algorithms now rather than wait until they figure out a better method to build qubits.

So anyway, it seems that photon qubits are even more expensive than aluminum cans.

Re:Do we really need to recycle photons? (1)

hicksw (716194) | about 2 years ago | (#41757537)

One with the energy equivalent to a Higgs Boson would be very exciting indeed. Maybe.
--
Strong ethanol force tonight the is..

Oh Great (0)

M0j0_j0j0 (1250800) | about 2 years ago | (#41745959)

Now we can have lectures about the sustainability of quantum computing and quantum computing goes green on an attempt to save the planet?

Optimize design - Simply guess "3" (1)

Anonymous Coward | about 2 years ago | (#41745961)

For all non-even numbers below 25, it's either prime or divisible by 3 (and since 25 is square, then for all numbers before 35 really)
As such, a quantum computer these days may as well always set the bottom bit in the answer to 1, and alternate randomly the second bit.

Re:Optimize design - Simply guess "3" (0)

Anonymous Coward | about 2 years ago | (#41747521)

I'm confused. Is 25:

- even?
- divisible by 3?
- prime?

What do you really mean by "then for al numbers before 35 *really*"?

Re:Optimize design - Simply guess "3" (1)

swalve (1980968) | about 2 years ago | (#41748403)

25 is not a number below 25.

factoring indistinguishable from division by 3 (1)

epine (68316) | about 2 years ago | (#41745975)

This won't impress the Babylonians until we get to 60 + 17.

Re:factoring indistinguishable from division by 3 (3, Funny)

rubycodez (864176) | about 2 years ago | (#41746175)

the number 35 is standing out back with a tire iron and would like to have a word with you....

In other words, they added a qubit (2, Insightful)

Anonymous Coward | about 2 years ago | (#41746115)

15 is between 2^3 and 2^4. 21 is between 2^4 and 2^5. Next stop, 51!

Re:In other words, they added a qubit (0)

Anonymous Coward | about 2 years ago | (#41747549)

Not 63?

Larger numbers factored already? (2)

JoshuaZ (1134087) | about 2 years ago | (#41746507)

Note that quantum computers have already been used to factor larger numbers. As TFA discusses and this preprint http://arxiv.org/abs/1111.3726 [arxiv.org] from about a year ago reports, there has been success factoring 143. But they didn't use Shore's algorithm but rather used an adiabatic algorithm http://en.wikipedia.org/wiki/Adiabatic_quantum_computation [wikipedia.org] . TFA makes a slightly incorrect claim that the adiabatic quantum algorithm "unlike Shore's algorithm, is not mathematically guaranteed to provide faster performance for larger numbers." This is misleading: Shore's is known to provide a polynomial time solution to factoring, but this is only known to be faster than the best known classical algorithms. In this context, we still can't prove that factoring is hard in the sense of taking more than polynomial time on a classical computer. Such a result is strictly stronger than P != NP http://en.wikipedia.org/wiki/P_versus_NP_problem [wikipedia.org] which is one of the biggest unsolved problems of mathematics today.

So.. what the hell IS Quantum computer anyway? (0)

Anonymous Coward | about 2 years ago | (#41746823)

And why should I care?

Re:So.. what the hell IS Quantum computer anyway? (2)

VocationalZero (1306233) | about 2 years ago | (#41747743)

Once, a long time ago, Slashdot was known as "news for nerds". We've come a long way, but every once in a while one of these sciency articles will slip through.

Simply pay this article no heed, good netzien, and I'm sure we can get back to our endless Apple vs Microsoft vs Linux vs liberal vs conservative vs cut vs uncut vs AMD vs Intel vs Oprah retard flame wars in no time. Wretched hives from the chans to even the AOL forums will be green with envy.

Re:So.. what the hell IS Quantum computer anyway? (0)

Anonymous Coward | about 2 years ago | (#41757069)

And here you are, adding to the noise that you claim that you detest...

Re:So.. what the hell IS Quantum computer anyway? (1)

VocationalZero (1306233) | about 2 years ago | (#41760427)

I detest drama, not "noise". But I do love AC trolls (:

They should be scared (0)

Anonymous Coward | about 2 years ago | (#41748727)

Given the rapid advance in the field people relying on cryptography SHOULD actually be scared. There is no value in waiting until the horse has bolted before fixing the gate. In this case, new technology won't roll itself out overnight. Particularly at the government scale. Better start thinking seriously about how you might secure your data and communications now.

Re:They should be scared (2)

insecuritiez (606865) | about 2 years ago | (#41749035)

Nonsense. It is still unknown if it is possible (even theoretically) to scale this up. One of the main reasons is quantum decoherence which seems to introduce errors faster than you can scale the machine.

There are plenty of reasons to abandon RSA (which assumes factoring to be hard) in favor of elliptic curves but these quantum factoring advances are not one of them. RSA keys must be huge in order to provide similar security that symmetric and elliptic curve algorithms provide with small keys. Also, it's somewhat likely that the NSA has 1) improved GNFS or another factoring algorithm and 2) has built dedicated cracking hardware. I fully except the NSA to be able to factor 1024 bit numbers today (perhaps even at a rate of one or more a month).

Re:They should be scared (2)

cryptizard (2629853) | about 2 years ago | (#41752007)

Good thing RSA seems to be the only widely used crypto tool that will be broken by quantum computing. Symmetric ciphers and hash functions are thought to be resistant to quantum attacks (besides the necessary doubling of key sizes that applies to everything, due to Grover's algorithm). We also have assymetric ciphers based on lattice constructions that are quantum-resistant, ready to step in and take over if RSA ever becomes impractical.

Nice to get in at the beginnnig (0)

Anonymous Coward | about 2 years ago | (#41751073)

It's cool to watch this tech start at the beginning, and see that factorized number grow exponentially. It's like baby steps.

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