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Making Cesium Atoms Do a Quantum Walk
An anonymous reader recommends an Ars Technica account of a breakthrough in efforts toward quantum computing. German scientists have managed to get cesium atoms in a state called a "quantum walk": basically a superposition of all the possible states of a particle. "Quantum walks were first proposed by physicist Richard Feynman and are, in terms of probability, the opposite of a random walk. A random walk might be modeled by a person flipping a coin, and for each flip he steps left for heads and right for tails. In this case, his most probable location is the center, with the probability distribution tapering off in either direction. A quantum walk involves the use of internal states and superpositions, and results in the hypothetical person 'exploring' every possible position simultaneously." In the abstract of the paper from Science (subscription needed for full-text access), the researchers say: "Our system allows the observation of the quantum-to-classical transition and paves the way for applications, such as quantum cellular automata."
Do we have a plan for when one day, our current methods of encryption all become breakable at once?
"And that geodesic is not shtraight either. Sho's I'll just superimpose my states back in da car and be on my way ..."
Cesium is an interesting element in that it is perfectly reliable. While some elements will differ in atomic weight due to random changes in their electron sphere radii and the number of neutrons in the nucleus, Cesium has a perfect vibration rate independent of external stimuli. It is so regular and reliable, in fact, that we base our entire measurement of time on clocks composed purely of Cesium.
If, as is demonstrated here, Cesium can be used to explore multiple quantum states in a regular and reliable fashion, the possibility to build quantum computers and automata based on Cesium goes way up. Not only would these "computers" function better than our current computers, they would always be 100% perfect (unless Intel manufactures them, lol) and not prone to error or breakage.
Not after an odd number of steps, in which case the probability of ending at the center is... zero.
As far as I know it, we have three main instruction sets. Integer, Floating Point, and Vector (SSE, MMX..etc). Would it more likely be that we would end up with the forth set being Quantum? Or, would it be possible to have an entire CPU quantum based?
Life is not for the lazy.
In other science news, German police scientists arrested a cesium atom and made it do a quantum perp walk. Afterwards, it deeply regretted its crimes.
Theoretically speaking, if we could get, say, an entire ship and all of its inhabitants to do this "quantum walk"...
wouldn't we be well on our way towards creating an improbability drive?
I'm probably hugely stretching this beyond what it means.
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"Left! Right! Left a wife and seventeen children in starving condition with nothing but gingerbread left! Left!"
with me? We can explore every possible position simultaneously.
What part of `yes no` don't you understand?
Please do not write further articles about quantum computing. This one was both factually inaccurate and unreadable. :P
fall in the same class of problems w.r.t to Quantum computing now?
You will never have experience until after you needed it.
Since women occupy every state at once, that is what makes me, a male, always wrong??? IS THAT RIGHT? IS IT?
In other news, two Cesium atoms were shot dead by Crip gang members in East Los Angeles. Eyewitnesses report the two Cesium atoms were seen performing the Quantum Walk at the time of the shooting.
You just got troll'd!
Reading /. stories that include the phrase "...first proposed by physicist Richard Feynman..." make my head explode.
John Titor! His Time machine used cesium to coordinate its location in time/space.
It seems that a week does not go by unless somebody, somewhere, claims yet another major advance in quantum computing. But has anybody noticed that this has been going on for at least a decade and we still don't have a quantum computer that we can put our hands on? It's obvious that some people need a constant flow of money to keep themselves employed. I just wish it weren't the public's money.
Quantum Computing Crackpottery
You may mod me down as a troll but I'm right, goddamnit! Quantum computing is both fraud and crackpottery.
or a scheme to pull in vast amounts of encrypted information to fish for things of value.
Too bad the entities with large sums of money are the same ones who want to sort through encrypted data looking for things of interest.
From TFS: "A quantum walk involves the use of internal states and superpositions, and results in the hypothetical person 'exploring' every possible position simultaneously."
Let's take a quantum walk!
At my age, I have trouble with a duck walk.
"Windows is like the faint smell of piss in a subway: it's there, and there's nothing you can do about it." - Charlie Br
http://fallout.wikia.com/wiki/Nuka-Cola_Quantum , If i remember correctly, Cesium was the isotope used in the game to "give that something extra" for the Nuka Cola Quantum :D
I'm imagining something like a cross between Mancini's Baby Elephant Walk and the Hamster Dance
ACK NAK RST
Quantum walk - is that like the moon walk?
Good thing - 'cause we won't be seeing that anymore.
What - too soon?
So let's say I get to this "Quantum Walking" stuff, really get to know this stuff and try it out... Say I go shopping by Quantum Walking... Will I be able to explore all the stores at once? Clothes, groceries That'd be useful!
The Sticky Issue - My TF2 Blog
You can get the full article from the arxive:
http://arxiv1.library.cornell.edu/abs/0907.1565
It is really a beautiful experiment. I have never seen such a demonstration of how deterministic the propagation of the wavefunction is. By simply running the experiment backwards they manage to get the atom to go back to it's initial position in the walk.
Here is the full text of the article, only posting it cause it's an amazing piece.
Take a Walk on the Quantum Side By Adrian Cho ScienceNOW Daily News 10 July 2009 If you're a fan of results that make your brain hurt, read on. Compounding one challenging concept with another, a team of atomic physicists has put a new twist on the classic "random walk"--an idealized wandering that is key for explaining the diffusion of one liquid in another and myriad other real-world phenomena. This time, researchers have set a single atom ambling according to the rules of quantum mechanics and found that it covers more distance than it would without them. The advance, reported today in Science, could have uses in budding quantum information technologies, the researchers say. But the real accomplishment seems to be the marrying of two classic physics concepts. In less politically correct times, physics professors explained the random walk as follows. Suppose a drunk stands under a lamppost, staggering to the right or left with equal probability. After some number of steps, N, he is likely to have taken a few more steps to the left than to the right, or vice versa. In fact, after N steps, on average the drunk will have moved a distance proportional to the square root of N from the post. That may seem like a pointless thing to know, but such a random walk neatly describes the motion of a molecule in a sample of liquid or electrons rattling around in a metal. Now, Michal Karski, Artur Widera, and colleagues at the University of Bonn in Germany have thrown the weirdness of quantum mechanics into the mix. A drunk or any other "classical" object must move either to the left or to the right. But according to quantum mechanics, a tiny particle such as an atom can actually move in opposite directions at the same time and end up in a so-called su perposition state in which it's in two places at once. There is a catch, though: Whenever somebody measures the particle's position, the delicate quantum state will collapse so that the particle is found in one place or the other. Taking advantage of all this, the researchers have made a single cesium atom take a "quantum walk" along a chain of spots of laser light formed by two opposing laser beams. Starting with the atom in one spot, they tickle it with radio waves to make it spin in opposite directions--up and down--at once. They then fiddle with the polarizations of the laser beams in a way that pulls the "up" part of the quantum state to the right and the "down" part to the left. That puts the atom in a hard-to-imagine state in which it sits in one spot spinning up while at the same time it sits in the next spot spinning down. The researchers then repeat the process again and again so that the atom ends up in a quantum state in which it occupies many light spots at once. When the researchers measure the atom's position, the state collapses to just one spot. But by performing the experiment many times, they can sketch out that state. And they find that, after N steps in the process, an average atom has moved a distance proportional to N from its original spot--farther than it would get classically. "It is difficult to imagine a cleaner, more textbooklike demonstration of the idea of a quantum walk," says Poul Jessen, an experimental physicist at the University of Arizona in Tucson. The advance could be more than academic, adds Reinhard Werner, a theorist at the University of Hannover in Germany. In principle, he says, by putting several atoms into the chain of light spots and letting them interact, it might be possible to construct a kind of quantum computer that could crack problems that a conventional computer cannot. A full-blown computer is a long way off, Werner says, but "this is a first step toward more complicated things." Did we lose you? Let us know in the comments section if you'd like to see us cover more complex physics stories like this one. ( skip to comments for this article ) Previous Article The editors suggest the following Related Resources on Science sites: In Sc
Quantum Walk? Call me back when also cesium atoms will do a moonwalk.
"In this case, his most probable location is the center, with the probability distribution tapering off in either direction"
Not true. His position will be sqrt(n) away from the center location, with a 50/50 chance of being either to the left or the right.
Do people even need to take a stats course any more? ;/
lt's not particularly quantum, is it? I'm afraid that the Ministry of Quantum Walks is no longer getting the kind of support it needs. You see there's Defence, Social Security, Health, Housing, Education, Quantum Walks ... they're all supposed to get the same. But last year, the Government spent less on the Ministry of Quantum Walks than it did on National Defence!
When talking about quantum computing, don't forget that someone has to write the programs. If you thing programming in a SIMD (Single Instruction Multiple Data) is difficult, try SIID (Single Instruction, Infinite Data).
Also remember that there are a few REALLY hard problems to solve before we can have a quantum computer compute anything. For example, to factor a key, you have to have two 'registers' and somehow get them to be the superposition of all primes less than the key value. That is, all non-primes are illegal states. Now you have to have them entangled in such a way that they collapse down to the two particular large prime factors of the key. That is, you have to somehow make all non-solutions to the problem illegal quantum states.
Anyone care to even pie-in-the-sky speculate how you make a quantum state contingent on primeness? Or on being a factor of a specific value? How about entangling 32 qbits together such that their legal states correspond to binary representations of all of the values the register might be and no others?
One day, we may know the answers to those questions, but it's going to be quite a while. There's every reason to believe that quantum computation won't be a matter of writing a program for a quantum computer, but rather a breakthrough in research that allows you to purpose build a quantum computer that solves a particular problem set. IF (and it's a big IF) we don't run into a necessary computational operation that the universe won't support in the quantum world or that it won't support in a way that's easier or faster than computing sequentially on a conventional computer, then we may one day have general purpose quantum computing.
If that works out, whatever language we program them in, list comprehensions will be the most important construct.
Instead of driving your 98 litre Hummer thirty yards to the burger joint three times today, why don't you stay in your trailer and learn to spell Aluminium properly?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."