## World's First Programmable Quantum Photonic Chip 156

MrSeb writes

*"A team of engineering geniuses from the University of Bristol, England has developed the world's first re-programmable, multi-purpose quantum photonic computer chip that relies on quantum entanglement to perform calculations. With multiple waveguide channels (made from standard silicon dioxide), and eight electrodes, the silicon chip is capable of repeatedly entangling photons. Depending on how the electrodes are programmed, different quantum states can be produced. The end result is two qubits that can be used to perform quantum computing. Most importantly, though, unlike existing quantum photonic setups which require apparatus the size of a 'large dining table,' this new chip is tiny: just 70mm (2.7 inches) by 3mm."*
## excellent. (Score:1)

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## Re:excellent. (Score:4, Funny)

## Re:excellent. (Score:5, Interesting)

That would be awesome to see - a hammock made of woven cat-5 cables.

Once saw the interconnect of a supercomputer/rack server "styled" into ocean waves, rather than just some snake-pit of cables.

## killer comment. (Score:2)

## Re: (Score:1)

That's why they tell you silicon valley types not to date porn stars, especially the ones who starred in the '24 hours of banging ' :D

Full-service shops do tend to rapidly increase the number of customers served, just ask McDonalds.

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Actually, the more pins are there, the more evenly your weight is distributed on them. 50 thousand pins are very close to a flat surface.

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So the OP might sleep like those babies

## Re: (Score:1)

Many babies cry a lot, sleep for a while,

piss and crap themselves,wake up, cry a lot. Repeat...So the OP might sleep like those babies ;).

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## ok (Score:5, Funny)

## Re:ok (Score:5, Funny)

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Doubt it. He said it in the first act instead of the last.

## Re:ok (Score:4, Funny)

## Re:ok (Score:4, Funny)

Yes, but only if you reverse the polarity first.

Don't forget to reroute it all through the main deflector dish.

## Re: (Score:2)

And re-route power from the shields. It's only dramatic if people are shooting at you while you wrestle with the finer points of quantum mechanics.

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Always wondered what happens to the ship, while the deflector dish is being used for something else than deflecting stuff...

## Re: (Score:2)

Sure, but first you'll need to channel that to an electromagnetic multiplexed photon phase inverter (EMPPIC) for that. Now you should be able to invert the phase post-processing. I have no idea about the tachyon results though. Good luck.

By the way, please don't rip a hole in the space-time continuum. Consider it a personal favor not too.Thanks.

## Re: (Score:2)

but can you link it to the inverted phase-induced sub-space harmonic protocol analyzer to initiate a modulated tachyon pulse?

Yes, you can, but due to the relatively primitive manufacturing techniques at this point in history, the phase variance of the pulse, being greater than 0.003, will not produce a sufficiently stable gateway between peripheral subspace domains to be of any use.

## Re: (Score:1)

## computing power scales exponentially (Score:5, Interesting)

For those who are unaware why qubits are so powerful: the computing power provided by qubits scales exponentially if compared to bits used in ordinary computing. For example if you had 20 qubits, that would be like doing simultaneous calculations on processor with internal register size of 1048576 bits. Roughly. That's orders of magnitude more than modern CPUs, which have about dozen of 64 bit registers.

## Re:computing power scales exponentially (Score:5, Informative)

oh, and I forgot to mention - that's also the reason why quantum physics is so difficult to model using our today's computers. Monte carlo and other rough estimations are widely used. Only simplest problems (think harmonic oscilator) have analytical (and crazy complex) solutions.

## Re:computing power scales exponentially (Score:5, Interesting)

I know qubits can be very useful at encryption/decryption/cracking and such, but I'm curious: what else would they be useful for? I mean, is there something that a typical desktop/workstation does today that could be improved by adding some qubit-based magic behind the scenes, similar to how GPUs (and FPUs before them) resulted in improved GUIs, games, CAD/CAM etc.? Or is this the kind of thing that's most probably going to remain restricted to specific fields, with very specific needs, for the foreseeable future?

## Re:computing power scales exponentially (Score:4, Interesting)

I wonder if it could be used for simulating consciousness. I mean, IBM's Watson is a machine with clever brute force implementation of language parsing and data retrieval. Quantum computing seems paradigm-shifting enough to effectively implement many Watson-type machines, perhaps.

## Re:computing power scales exponentially (Score:4, Insightful)

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## Re:computing power scales exponentially (Score:5, Insightful)

that's an arse-backward definition of "simulation" that you have.

it needs to be able to make meaningful predictions as well.

for example, a VFX explosion in a space-opera versus a simulation of a nuke explosion on a supercomputer at Los Alamos

## Re: (Score:2)

interesting ideas! please present me with some proofs.

## Re: (Score:2)

i had no need to define a term i did not use.

your shadow smells like shit, feeb.

## Re: (Score:2)

## Re:computing power scales exponentially (Score:5, Informative)

The general rule for qubits seems to be anything that requires a unique solution but has to consider every possible combination of boolean states. Since they are Boolean zero or one values, that leads to cryptography because a relatively few number of bits would be required; 256,512,1024.

GPU's do floating-point calculations in parallel, which is really good for those problems which have to apply the same algorithm to different data points, like CFD, physics, AI, image and signal processing.

To represent floating-point data would require at least 16 qubits for half-floats, 32-bits for IEEE 754 standard floats, and 64-bits for doubles. But to do anything useful like CFD, would require storage of the entire state of the system which would require gigabits of data.

Unless someone could shrink the problem of CFD modelling down to atomic scales using phantom atoms, and overlapping qubits onto the same logic, GPU's won't have any competition.

## Re: (Score:2)

Now your going to suggest finding all of the Mercian Primes under 10^1000 or something. Just what we needed, more goddamn Mercian Primes. They're all over the place.

## Re: (Score:2, Informative)

It's Mersenne primes. And use powers of 2, not 10.

## Re: (Score:2)

Maybe there's an easier way than qubits. What if you could use natural resonance of something like a torus pipe. Set up one frequency to represent the quantity you are trying factorize as a ratio of the quantity to the circumference of the torus. This would define a standing wave pattern. Create some white noise into the system at one point. Factors of the value would then create points of minimum and maximum amplitude around the torus.

## Re: (Score:2)

...what else would they be useful for? I mean, is there something that a typical desktop/workstation does today that could be improved by adding some qubit-based magic behind the scenes...?

That is, will it run Emacs, LaTeX, and other important stuff? :-)

## Re: (Score:2)

From the article it seems that one thing that we "just have to discover.. " we know it will be good at some applications but only actual use/engineering will fill in all the blanks..

## Re:computing power scales exponentially (Score:5, Informative)

http://en.wikipedia.org/wiki/Quantum_computer#Potential [wikipedia.org]

## Re: (Score:2)

Quantum computers are sort of the ultimate parallel systems. That does mean they only work well on really parallel problems though. "Cracking encryption" means factoring large numbers - it goes much faster if you can try all the possibilities at the same time. Quantum computing may well remain a niche thing though, good for physical simulations and things like factoring (until everyone quits using that kind of encryption). Or maybe we'll think of entirely new uses.

## Re: (Score:3)

what else would they be useful for?

https://secure.wikimedia.org/wikipedia/en/wiki/Grover's_algorithm [wikimedia.org]

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We could make mighty fast logical reasoners, text search would become even faster etc.

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I suspect this is powerful enough computing power that there will be an argument to keep it restricted to "the cloud". Too much power for the average citizen, more than anyone but a terrorist would need, that kinda thing.

Erm, that's what they said about the first ever computer, you know, the quote that went: "there is a global market for a total of 8 computers" or something.

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With qubits you can, in principle, also solve problems (much faster) which are NP-hard (see: http://en.wikipedia.org/wiki/NP-hard [wikipedia.org]), the traveling salesman problem for instance.

I guess it depends on your defintion of "much".

Wikipedia: "Grover's algorithm can also be used to obtain a quadratic speed-up over a brute-force search for a class of problems known as NP-complete"

So perhaps you'll bring some of the smaller cases into the realm of possibility but in the long run, its still exponential...

## Re:computing power scales exponentially (Score:4, Insightful)

Definitely. However right now we do not have 20 qubits in a device, we have 2 qubits today. If progress in physics and electronics allows us to have 3 qubits in 18 month, 4 qubits in 36 months and so on, we have just reinvented the quantum version of Moore's law.

## Re:computing power scales exponentially (Score:5, Informative)

Oh, we already have a quantum version of Moore's law [quantenblog.net]. However, the time constant for doubling is on the order of six years and not 18 months.

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Actually if the number of qubit we can manage doubles within some time constant, then this is cool, because I was assuming that it would increase *linearly* with time. If the qubits scale linearly and the traditional computers exponentially, ten quantum computers may never catch up to classical ones. However with exponential qubit growth they do have a chance irrespective of the time scale.

Your linked article says that quantum computers will become interesting at about 50 qubits and that it might happen by

## Re:computing power scales exponentially (Score:4, Interesting)

I think he made it up. I am not making up (but could be completely wrong) that coincidentally the difficulty of preventing decoherence scales exponentially. And that is the primary limiter to # of qubits and performance, more or less correct?

In the very long run, I think quantum computing is going to be very much like DSP, in that the "hard work" is handling the analog signals to get "the problem" in and out. Inside ye olde DSP processor, a couple gnomes magically make it work, and superficially seem to be the hard part, at least partially correctly as some of the math is hideous. But the real problem is the unavoidable analog/RF work.

Kind of like how supercomputing is defined as taking a CPU bound process and making it an IO bound process, more or less.

## Wake me when they get to 2048 qubits (Score:2)

I think he made it up. I am not making up (but could be completely wrong) that coincidentally the difficulty of preventing decoherence scales exponentially. And that is the primary limiter to # of qubits and performance, more or less correct?

This is why I more or less will ignore quantum computing unless they can get the number of qubits up enough to be useful.

Wake me when scientists make a 2048-qubit computer. The Xbox 1 public key and I have a score to settle.

## Re: (Score:3)

## Bad news for crypto (Score:5, Interesting)

If what you say is true, this is truly bad news for cryptography. Algorithms like AES owe their security largely to the fact that brute-forcing all of the keys is generally impractical; with a 256 qubit machine, AES 256 would be cracked in *a single clock cycle*.

If they can do this with two qubits, why not 4? Why not 8, or 128, or 512?

In the same way the WWII cipher designers probably had a hard time imagining that in 40 years there would exist a machine which could crack their ciphers in real time, the designers of block ciphers like DES and AES probably had a difficult time imagining that their ciphers would be insecure in mere decades. DES took 30 years before brute force became practical; will AES survive even 20?

It was just 20 years from the invention of the transistor to the first 32 bit computer. How long will it be before a machine with more computing power than in all of recorded history can be built on something the size of a postage stamp, for a few dollars?

## Re:Bad news for crypto (Score:4, Informative)

## Re: (Score:2)

If they can do this with two qubits, why not 4? Why not 8, or 128, or 512?

Quantum decoherence. [wikipedia.org]

## Re:computing power scales exponentially (Score:5, Informative)

## Not exactly exponentially (Score:5, Insightful)

The computing part does indeed act on every combination your register can have at the same time. An exponential speedup here, that part is right. What is missing on your post is that reading the result is kind of hard. We only know how to get usefull data from a few kinds of calculation, and we don't know if it is possible to get anything usefull from the general case.

The good news is that if we ever discover a way to read the result of a general computation (if it is possible), we'd have discovered a nondeterministic computer. And forget about P ?= NP.

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Yeah well but this one only has 2.

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That's false; the power increases polynomially, not exponentially (usually power of two). This is the reason quantum computers can't solve NP-hard problems asymptotically faster than classical ones.

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yes exactly the same as as every other processor

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## Bristol group (Score:3)

I assume this is the same group (how many quantum computer groups are there likely to be in Bristol?) that did the whole "lets run Shors algorithm on a silicon etched chip" a couple years ago. So the new news right now is ... Or is this a re-reporting of that historical event, or another paper about that historical work? I'm just trying to figure out the whole timeline thing here.

Hey /. editors, the recent interviews have been very interesting and all that, I'm just thinking interviewing the quantum group in Bristol would be even more interesting...

## Re:Bristol group: uncertainty (Score:5, Funny)

how many quantum computer groups are there likely to be in Bristol?

You can either know where they are, or how many there are - but not both.

## Interesting bench scale physics survives (Score:1)

## Re: (Score:2)

Just think what would be possible if the megalomaniacs weren't hogging all the money.

We'd finally find out what happens when the meek inherit the Earth?

## Entangling photons is a bad idea. (Score:5, Funny)

## Re:Entangling photons is a bad idea. (Score:5, Funny)

## Re: (Score:2)

It is hard because you can't tell them apart.

## Imagine... (Score:2)

a beowulf cluster of these...

Had to go there, this is /. afterall...

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## The Downside (Score:5, Funny)

Unfortunately, after you program it you no longer know where it is.

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No. But I know how fast it's going...

## Result=99% of CPUengineers will be without job ? (Score:2, Insightful)

Help me out.

This would have happened sooner or later, and I am assuming it happened. Quantum computer are here to stay.

Question is, what this means to general community of engineers and software developers ?

I am perfectly aware that we don't have Hardware that is capable of supporting the work of this chip (RAM and HD don't make sense). Maybe in another 15 years.

Does it mean complete shift of computing paradigm ?

Instead of 100 servers, we have just small black-box in a backroom ?

What will happened to all th

## Re: (Score:1)

## Re:CPUengineers will be without job ? (Score:5, Insightful)

Quantum computers are not "here" in any meaningful sense. Nobody ever has demonstrated a meaningful larger-numbers quantum computation (say, with numbers > 1000). At the moment, the there is no proof these will even work. It is still entirely feasible that the theory is wrong and large quantum computers are not possible or not useful. Even some tiny deviations from the current theory could cause that. Remember the results have to be physically measured and the input has to be physically put in. Both operations with huge, huge errors when compares to the precision classical computers achieve.

Then, even if meaningful sizes can be built (which is entirely unclear at this time) they are not effective or efficient for most problems.

Example: For breaking ciphers like AES, you get a square root on the key size, i.e. breaking AES-256 becomes as difficult as breaking AES-128 (both by brute force). Breaking AES-128 by brute force without quantum computers is quite infeasible in this universe. Breaking AES-256 by brute-force with quantum computers is quite infeasible in this universe as well.

Forget about any large data-set problems as well. Unlike classical computers, you cannot break problems down for quantum computers. You always have to solve the whole thing in one go, or you lose the advantages.

Bottom line: This is not a revolution, even if it turns out not to be bogus in the first place.

## Re: (Score:2)

let sqrt(x) = x/2

oh wait, i think you got something wrong there.

## Re: (Score:3)

log2(sqrt(x)) = log2(x)/2

(by key size, he meant the magnitude of the key, not the number of bits in the key)

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Indeed. I should have said "square root of the key-space" instead to be clear. So half the bits, i.e. square root of the number of possible keys.

## Re: (Score:2)

Quantum theory doesn't have to be wrong for quantum computers to be impossible. We know that quantum effects are only present microscopic and not macroscopic systems (with some few, very particular exceptions like crystals, plasma etc). It is plausible that there are yet unknown consequences of the standard QM model that would prohibit quantum effects in sufficiently complex systems, thus "forbidding" quantum computers without making quantum mechanics wrong. I for one hope there are not.

## Re: (Score:2)

Indeed. Say, for example you get a random (in practice) unavoidable measurement error that increases in some unpleasant fashion with the number of entangled qbits. I.e. the calculation could still be done, but the results could not be read with the required precision. That would leave the theory intact, but would kill cipher-breaking and many other applications. For this to happen, it could be enough that building a quantum-state reader for larger entangled sets (remember, you have to read them all at once

## Re: (Score:3)

Nothing happens to engineers. They just design quantum chips instead, at worst (but most likely: a mix of quantum and conventional computers is still required). Most likely it will still be decades yet before most even need to care.

Nothing happens to programmers. A handful of library designers will work out the interesting bits. The rest will continue building applications on top of the libraries as usual.

## Mmmm (Score:1)

Sounds delicious.

## How many of those do I need to play solitaire? (Score:2)

heck, I'll settle for snake, I'm an easy game consumer to please

## If someone... (Score:2)

Years ago, if someone had told me I might actually die by having my heart vaporized, in situ, by a T-101, I would have laughed.

http://en.wikipedia.org/wiki/Quantum_computer [wikipedia.org]

http://en.wikipedia.org/wiki/Artificial_intelligence [wikipedia.org]

http://en.wikipedia.org/wiki/Self-replicating_machine [wikipedia.org]

http://en.wikipedia.org/wiki/Military_robot [wikipedia.org]

http://en.wikipedia.org/wiki/Directed-energy_weapon [wikipedia.org]

http://en.wikipedia.org/wiki/Skynet_(satellite) [wikipedia.org]

Not so funny anymore.

## Quantum Photonic (Score:1)

## Quantum Co-Processor? (Score:3)

## *YAWN* (Score:2)

## Blow your mind! (Score:2)

OK, what if this universe is just a simulation, running on a huge (comparatively) quantum computer. Now what if it was such a wicked simulation, that some beings within it, became more than just simulations but rather self aware. What if they started poking around at the fabric of the universe (being a simulation), and start to see some of the underpinning of that quantum computer. So they build quantum computers. Eventually in an effort to discover the answers to their questions, they try to model a univer

## cool! (Score:1)