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Two-Photon Walk a Giant Leap For Quantum Computing
ElectricSteve writes "Research conducted at the University of Bristol means a number of quantum computing algorithms may soon be able to execute calculations of a complexity far beyond what today's computers allow us to do. The breakthrough involves the use of a specially designed optical chip to perform what's known as a 'quantum walk' with two particles ... and it suggests the era of quantum computing may be approaching faster than the scientific establishment had predicted. A random walk – a mathematical concept with useful applications in computer science – is the trajectory of an object taking successive steps in a random direction, be it over a line (with only two possible directions) or over a multi-dimensional space. A quantum walk is the same concept, but translated to the world of quantum computing, a field in which randomness plays a central role. Quantum walks form an essential part of many of the algorithms that make this new kind of computation so promising, including search algorithms that will perform exponentially faster than the ones we use today."
We soon need to certify in quantum-mechanical logic to write software?
Any good resources?
I think we can keep recursing like this until someone returns 1
when can I have one on my desktop, and will it make completely immersive games possible. Sure search algorithms are great and all, and so are other scientific wonders that can come about from quantum computing, but unless I can have fun with it at home it does fuck all for me.
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Horror & SciFi Erotic Nudes
Didn't we just have an article on slashdot about the realities and exaggerations of the capabilities of quantum computing and what they would actually do? I hope this discovery is really going to do what the author hopes it means, and is not an exaggeration.
into a bar... wait... where am I?
Here's how it looks under a microscope
For justice, we must go to Don Corleone
For example, assume there are... cans... situated in the area around me. Inside these cans are... recyclable materials. I'm on a... Segway. What's the optimal path I should take to loot\h\h\h\hretrieve the items in the cans in the least amount of time?
According to the quantum computing video from a while ago (I think it was 90 minutes or something, I just watched 20), a quantum computer is designed for the problem it solves- they aren't general purpose like the processors in use today. As far as I understood from the video*, quantum computers are mostly just useful for doing calculations related to quantum physics.
*If I'm wrong/misleading, please correct me.
My webcomic
Well, it seems there is no article yet to be read, and I couldn't understand anything from the press release. What does it mean a "one photon quantum walk", and what is the difference from any other kind of transformation that happens on a photon? Also, what is the difference of "two-photon quantum walk" and normal interference?
Or, in other words, what did they actualy do?
Rethinking email
youtube.com/watch?v=M60N0PCUgVQ&feature=player_embedded
Because people always get it wrong every time a QC article hits slashdot, here's a link to my previous, highly-modded (upwards) post on QC:
http://slashdot.org/comments.pl?sid=1285849&cid=28520061
Quantum computers can do some cool things, but mostly solve problems no one cares much about (except a few of us mathematicians)
A Quantum Computer will declare a private island for you, build a jet plane, and figgin' fly you there.
That's a win-win!
Summary is wrong. Quantum algorithms cannot provide "exponential" speedup of any problem. If they could, we would be able to [probably] solve NP-complete problems with quantum computers, and that hasn't been proven yet. The best they can do is "super-polynomial" speedup of classical algorithms.
Google "quantum algorithm zoo" to see all the known algorithms and their speedups (and how unexciting most of them are).
Yet Another Flying Car
-Mesotach
Seams like it about time to start putting 5 years of real world quantum programming experence on the old resume.
I believe the technical jargon makes it sound much more complicated than it is. Understanding what the scientists did requires knowing about 'random walks' and their significance. Think of a typical processor working on a problem that involves random walk sequences. Now imagine if that was replaced by getting 2 photons to calculate the 'random walk' part of the problem -- speed is massively increased, and quantum superpositions are now hopefully being utilized. The problem, in many cases, may have just become exponentially easier and faster.
Just another "small step" out of thousands we are blessed with being able to witness. Patience is a virtue.
Peter Gibbons: What would you do if you had a million dollars?
Lawrence: I'll tell you what I'd do, man: two photons at the same time, man.
I just can't comprehend quantum computing and quantum mechanics in general.
What absolutely derails me is the talk about randomness, probability and statistics inherent with this field. The word chance gets mentioned a lot and that just stops me in my tracks.
In programming there is simply no room for chance. Algorithm must always return the same result given same parameters. 1 + 1 must always return an exact, perfect value of 2 no matter how many times it is executed.
But from what I read, in quantum world you can only say that this particular action will result in probability of 0.99999999999 (Number of nines vary per setup) of returning that particular result. Very large amount of nines sounds reassuring, but given the speed of CPU's processing an instructions billions of times per millisecond, give enough execution time and eventually you will hit that one time when the result will not be what is expected.
And one wrong result will put the entire program into an undefined state.
When every instruction has a chance (VERY minute but still) of failing how do you even start to approach an issue of debugging. In order to plan my program flow I need the stability of my assumptions. And this is even before we start talking about the really weird parts of quantum mechanics (Superposition of states, etc).
Perhaps I just don't understand the field of probability and statistics. Quantum computation is a reality thus randomness is not an insurmountable hurdle that my mind makes it to be. I would really appreciate if someone with some knowledge in the area would try to explain (Or provide me with a link that directly addresses this issue) how the chances of particle states get converted into solid 100% reliable predictability.
Come on, Scott Bakula was taking random quantum walks back in the late 80s, get with the times people!
Monstar L
Grover's search algorithm gives only a quadratic speedup.
Two photons walk into a bar, orders a round of IPA and asks "How much do we owe?"
The barkeep says "For you? No charge."
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Finally we'll be able to run bogosort efficiently
Let me provide some context. This research group specializes in manufacturing arbitrary waveguide structures on chips, then coupling particular quantum states of light into them. The idea is to turn a large optical table worth of mirrors into a tiny chip. What they have done here, is allowed a two photon input state to interfere with itself in the waveguide structure.
While interesting technically, it isn't exactly a huge leap forward because the interaction is linear. What's needed for deterministic quantum computation with light is a very non-linear process. The waveguide structure can replace a large number of mirrors and compact the optics into a tiny space but, at the end of the day, mirrors aren't all that interesting for quantum computation. It is, however, worthwhile because of the impressive miniaturization and the technical challenge of working with quantum light in such tiny structures. A strong non-linear component will be needed for true optical quantum computation, but chips like these show a lot of promise for handling a lot of state preparation and measurement.
So if this is the future...where's my jet pack?
With your eyes open or closed, you're still in your parent's basement.
I tried to think of a good sig, and this wasn't it.
Expert typing and speling skills.
Two photons walk into a bar...
Wait, didn't Brian Greene already tell this joke?
So far, claims from quantum computing researchers hungry for funding resemble that of some other areas that have consistently not delivered for the last 50 years or so. All these isolated demonstrations mean nothing for quantum computing, because different from normal computers, you cannot build them up from parts you understand. A quantum computer is always only one unit, there are no modules or sub-components. Compare that with a traditional computer and it becomes obvious that the only proof of scalability for a quantum computer is to build the size you claim you can. And until that is done, everything else is basically wishful thinking. This also means that at this time, it is quite possible that quantum computers of meaningful power are fundamentally infeasible in this universe.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.