Quantum computing is interesting to me. Anybody care to share what they know about it? It's an emerging field, realted to spintronics. I'd like to find out more...but it's definately highly technical....=)
Quantum Computing??
- Thread starter chocbrucemousse
- Start date
Do a search in the archives for "quantum comput" (without quotes, and use comput instear of computer so that it will retrieve the string quantum computer(s) and quantum computing). This has been discussed before.
From the limited knowledge I have about quantum computing, I believe what I gathered from the theory of quantum computing is that it relies on areas of quantum mechanics never really explored. Quantum computers would use matter that doesn't even exist in this universe, but matter that exists in parallel universes making its computational power nearly infinite. Highly technical indeed and highly theoretical for now. If a quantum computer ever was built it would be the end of the field of encryption as we know it. Any encryption algorithm could be brute forced, even ones that have a keyspace that is greater than the number of atoms in the universe. And that would just be the beginning...
This is all wrong! Even if the area of quantum mechanics that quantum computers use is a bit exotic it is quite well understood(should be included in any undergraduate course in quantum mechanics) and in order to build a quantum computer you definitly use ordinary matter.
The most succesfull implementation so far uses standard NMR machines (same typ you would find in an hospital), by using NMR a 7-bit quantum computer was built and tested about a year ago. Other types of quantum computers use solid state technology, mainly superconducting electronics, you can also use optical systems.
We already have quatum computers with a few bits, the problem now is to scale it up to several thousand bits so that it becomes usefull and that is VERY difficult.
This is correct. Also, a little side note, a quantum computer does not use a bit as we know it (1 or 0), It uses a "qubit" (quantum bit). A qubit is basically a spinning nucleus. When it spins up, it is 1, down, it is 0, and in quantum mechanics, a nucleus can spin both ways, at the same time, and this is called the superposition. Check out this article from Popular Science, it discusses the future of traditional computer, DNA computers, and Quantum Computer: Here.
For more information on the topic, check out scientific american....sometime last year there was an issue about it. http://www.sciam.com
also Oxford has some interesting information. http://www.oxford.edu
also Oxford has some interesting information. http://www.oxford.edu
No, it is not all wrong. I have a book about quantum computers. I'll get you the book I am referencing if you want.
"Quantum computation, which is now in its early infancy, is a distinct further step in this progression. It will be the first technology that allows useful tasks to be performed in collaboration between prallel universes. A quantum computer would be capable of distributing components of a complex task among vast numbers of parallel universes, and then sharing the results."
From: The Fabric of Reality by David Deutsch page 195 Paragraph 2
Next time think before shooting your mouth of and saying someone is all wrong. Thank you.
He never said what specific topic you said was wrong. You said a quantum computer would use matter that does not exist. That in it self is wrong. Quantum computers do exist, albeit in a primitive state. THERE EXIST QUANTUM COMPUTERS using elements that are fairly common. Read the article I posted, so you think before shooting your mouth off.
What I meant was that future quantum computers would use matter that doesn't exist IN THIS UNIVERSE. Not matter that doesn't exist at ALL. Read the entire sentence, then read The Fabric of Reality by David Deutsch. Sure they have primitive quantum computers now that use matter here in this universe but the theory of quantum computing includes using matter in parallel universes. What do you not understand about that?
Edit: and yes he didn't say a specific topic, he said I was ALL wrong. But I'm not so his statement is false.
In fact I DO think Deutsch is wrong, the thing with quantum mechanics is that you can intepret it it many diffrent ways. The "parallel universe" intepretation was quite popular in quantum philosofi (yes, there is such a thing), if I am not misstaken it was introduced by David Bohm a long time ago.
Don't get me wrong now, Deutsch is very good at what he does (he invented one of few usefull quantum algorithms) but he is quite alone in his interpretation, I suspect the "parallel universe" part simply sounds good in books. Of all the people I have meet who are working with quantum computing I can not think of one who uses this interpretation.
Let me clarify, if you belive that quatum computers uses "parallel universes" then you are also saying that ALL quantum-mechanical processes takes place in "parallel universes" or whatever you want to call it.
In quantum mechanics you can never be sure of anything, the only thing you can do is calculate propabilities, let me give you an example: Lets say the probability for an electron to jump from an S to a P state is 0.5. there is also a probability 0.5 that it will instead jump to the D state (making the total probability for the electron to do something equal to 1 which makes sense), what will the electron do? Most people (including me) would say that the electron will jump to either state (that is, it will en up in the P OR D state) when I measure it, the "parallel universe" people would say the electron does both, creating two parallel universes in the process, one universe for each outcome (meaning that one "me" will measure P and the "me" in the parallel universe will measure S),
I should point out that this is the most extreme parallel universe interpretation, there are variations.
Since quantum computing is based on the superposition principle, which basically tells you that the electron can exists in BOTH states until you measure it, Deutsch claim is that the electron is really sitting in two different "dimensions".
Fortunately, the math is the same no matter which interpretation you prefer (which is why Deutsch is still a highly respected scientist). But, me and most people working with quantum computing thinks Deutsch?s intepretation is quite strange
Don't get me wrong now, Deutsch is very good at what he does (he invented one of few usefull quantum algorithms) but he is quite alone in his interpretation, I suspect the "parallel universe" part simply sounds good in books. Of all the people I have meet who are working with quantum computing I can not think of one who uses this interpretation.
Let me clarify, if you belive that quatum computers uses "parallel universes" then you are also saying that ALL quantum-mechanical processes takes place in "parallel universes" or whatever you want to call it.
In quantum mechanics you can never be sure of anything, the only thing you can do is calculate propabilities, let me give you an example: Lets say the probability for an electron to jump from an S to a P state is 0.5. there is also a probability 0.5 that it will instead jump to the D state (making the total probability for the electron to do something equal to 1 which makes sense), what will the electron do? Most people (including me) would say that the electron will jump to either state (that is, it will en up in the P OR D state) when I measure it, the "parallel universe" people would say the electron does both, creating two parallel universes in the process, one universe for each outcome (meaning that one "me" will measure P and the "me" in the parallel universe will measure S),
I should point out that this is the most extreme parallel universe interpretation, there are variations.
Since quantum computing is based on the superposition principle, which basically tells you that the electron can exists in BOTH states until you measure it, Deutsch claim is that the electron is really sitting in two different "dimensions".
Fortunately, the math is the same no matter which interpretation you prefer (which is why Deutsch is still a highly respected scientist). But, me and most people working with quantum computing thinks Deutsch?s intepretation is quite strange
CallTheFBI, as f95toli said, the fact that quantum effects are very counter-intuitive and has led to many different theories to explain them. The truth of the matter is that as of now, no one is "right" and no one is "wrong" since we can't really prove any of these interpretations to be the correct one.
chocbrucemousse, are you interested in "pure" quantum computers such as the one described f95toli or spintronics? Though I am by no means an expert about this, I was under the impression that spintronics was the science of using quantum spin as a carrier information in a classical computer (I think I read it in SciAm, now that I think of it). I think they said that within a few years it is likely that devices that use spintronic devices will start hitting the mainstream as it seems quite feasible. Pure quantum computers on the other hand are probably a ways off right now since it is very difficult to create a reliable quantum computer of any size given it's functioning.
I'm sure if you look up Amazon you can find some decent books on either subject
chocbrucemousse, are you interested in "pure" quantum computers such as the one described f95toli or spintronics? Though I am by no means an expert about this, I was under the impression that spintronics was the science of using quantum spin as a carrier information in a classical computer (I think I read it in SciAm, now that I think of it). I think they said that within a few years it is likely that devices that use spintronic devices will start hitting the mainstream as it seems quite feasible. Pure quantum computers on the other hand are probably a ways off right now since it is very difficult to create a reliable quantum computer of any size given it's functioning.
I'm sure if you look up Amazon you can find some decent books on either subject
Actually there is already evidence that the parallel universes do exist. I believe that there have been experiments done in a vacuum where they shined a light through a slot and when the light hit the other side there were photons where they couldn't explain where they came from. In other words the size of the beam of light was larger than it was supposed to be. One of the top theoretical physicists from England is working out the quantum mechanics of the theory. There was an article about it in Discover magazine awhile back. So while the theory is kind of "out there" it does actually have real world evidence supporting it.
I for one hope the theory is true. If it is true then there are an infinite number of us out there living in an infinite number of possible worlds and maybe when we die in this universe, whatever makes us conscience here would be reproduced in another universe and we are reborn.
I am not saying this is wrong (even if I I need to see some pretty onvincing experiments before I believe it). The point I was trying to make is that you do not need to use exotuc materials, a parallel universe etc. in order to understanf quantum computing. What we are trying to do is to use processes that occur in nature all the time to do computation in a new and radical way.
.
.
I'm a little too lazy to read the above posts, but as I understand it, quantum computing is when the various states of an atom (I think its 16) are used as opposed to 0 and 1 (only 2 states) The calculations also take place in alternate universes and so they are instantly done because they were done before they were requested. Thats my understanding of it anyways. Correct me if I'm wrong.
That's how I understood it too and same with physicist David Deutsch. f95toli and his friend krazikid seem do disagree vehemently about the parallel universe part.
hfhf6: That is incorrect, a quantum computer normaly only uses two states (it can use more but so can ordinary computers), the point is to create superpositions of these states. And it doesn't have to use atoms. most implementations use solid state technology where the quantum-bit is a device on a silicon chip (the NMR people use states in molecules, the energy states in atoms are too hard to manipulate). The only thing you need in order to build a quantum computer is a tw-state system which interacts very weakly with the rest of the world so that it can create a superposition of states (also known as a Schrodinger Cat-state)
What im basically saying is that there is no difference between the way a quantum computer works and the way energy states in an atom works, if you are saying that you need alternate universes in order to do quantum computing you are also saying that you need a alternate universes to build a Laser.
I should point out that I don't think Deutsch means "parallel universe" in the Star Trek sense, it is more subtle than that, but I still don't agree with him.
What im basically saying is that there is no difference between the way a quantum computer works and the way energy states in an atom works, if you are saying that you need alternate universes in order to do quantum computing you are also saying that you need a alternate universes to build a Laser.
I should point out that I don't think Deutsch means "parallel universe" in the Star Trek sense, it is more subtle than that, but I still don't agree with him.
I've heard of the Schrodinger Cat thing, very interesting. I think that quantum computing has something to do with the slit in a piece of paper experiment. If single atoms are are sent through one slit in a wall (or whatever) and is detected on a flat plane on the other side, it shows up in a pattern of either 2 or 4 lines (sorry can't remember which) and this is because the atoms are affected by energy and forces from another universe that cause the atoms to line up in that particular formation every time. About the solid state computing, I heard that the major challenge of quantum computing was controlling the atom singularly and influencing it's states to perform calculations. Maybe I'm wrong, you seem very knowledgable about this.
I never disagree'd with the parallel universe theory. What I was saying is that a quantum computer does not have to use that. A quantum computer, as they are currently known today, rely on superposition. If you read the article I posted, you would see that they have already built quantum computers. I personally believe in a multiverse theory of the galactica, but that does not have anything to do with quantum computers in the here, and now.
earthman
Golden Member
- Oct 16, 1999
- 1,653
- 0
- 71
The "parrallel universe" thing is totally mistated most of the time. Its a way of describing the extra dimensions which probalby exist at the subatomic level, and are far too small to affect anything we might see on our physical level. Most people have this concept of a mirror image of themselves doing the same thing at the same time in some other antimatter universe which is ridiculous.
No it isn't. That is part of the theory. It was in Discover magazine awhile back. I wish I could find it, it was laying around my house somewhere.
This is what I was talking about before with the light experiment:
The weird thing is that if you put detectors there they only see the photons going through one of the slits.
The weird thing is that if you put detectors there they only see the photons going through one of the slits.
silverpig
Lifer
- Jul 29, 2001
- 27,703
- 12
- 81
That interference pattern will happen whether you send photons through two slits, or trucks through two tunnels...
A better description of what happens would be to say that the photon passes through both slits at once and interferes with itself. Photons are "fuzzy" and are not point particles (actually, nothing is truly a point particle), and thus has most of it's "being" spread over a small region of space, and all of its being spread over a large area of space. What little part of the photon goes through slit A interferes with what part of the photon goes through slit B, thus causing the interference pattern.
To say that the photon interferes with another photon in a parallel universe isn't accurate in my opinion. Why can this other photon interfere with it's mirror image only if two slits are involved? Why doesn't it interfere if only one slit is involved, or no slits for that matter?
A better description of what happens would be to say that the photon passes through both slits at once and interferes with itself. Photons are "fuzzy" and are not point particles (actually, nothing is truly a point particle), and thus has most of it's "being" spread over a small region of space, and all of its being spread over a large area of space. What little part of the photon goes through slit A interferes with what part of the photon goes through slit B, thus causing the interference pattern.
To say that the photon interferes with another photon in a parallel universe isn't accurate in my opinion. Why can this other photon interfere with it's mirror image only if two slits are involved? Why doesn't it interfere if only one slit is involved, or no slits for that matter?
Remember, the parallel universe effect only occurs when there are alternative outcomes. If the photons only have one slit to go through then that is the event that occurs in all the universes, since there are no alternatives, it HAS to go through that one slit. Since that is the event that would occur in that universe you wouldn't notice any difference. Thus, at least two slits must be there for there to be an alternative outcome so in some of the universes an individual photon goes through slit A and other universes the photon goes through slit B. Anyways, that is my unqualified answer. Just a logical guess from what I am reading in the article.
TRENDING THREADS
-
Discussion Zen 5 Speculation (EPYC Turin and Strix Point/Granite Ridge - Ryzen 9000)- Started by DisEnchantment
- Replies: 25K
-
Discussion Intel Meteor, Arrow, Lunar & Panther Lakes Discussion Threads
- Started by Tigerick
- Replies: 21K
-
Discussion Intel current and future Lakes & Rapids thread- Started by TheF34RChannel
- Replies: 23K
-
-
Facebook
Twitter