| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
22 Sep 2006 08:37:28 PM |
| Object: |
Quantum Computers and Classical Computers |
I apologize in advance if this question appears dumb as I warn that I
am not a physicist. I am a big fan of Physics and I have great interest
and enthusiasm to learn all I can about it. This question is regarding
computers - quantum and classical to be exact.
I am confused... what is the distiction between a classical computer
and a quantum computer? Correct me if I am mistaken but, isn't a
classical computer still a quantum-mechanical device? I mean, if I
don't recall incorrectly from my college Physics (I was very good at
it), computer components at the foundation level are described using
Quantum Mechanics - electron flow through semiconductors, junctions,
interferance, etc. Therefore, by its very nature, a classical computer
depends on many quantum mechanical processes, just as a Quantum
Computer does. If this is the case, what is, then, the purpose of a
Quantum Computer?
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| User: "Nicolaas Vroom" |
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| Title: Re: Quantum Computers and Classical Computers |
06 Oct 2006 08:57:31 AM |
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<ekcientifico77@yahoo.com> schreef in bericht
news:1158975447.944717.48210@d34g2000cwd.googlegroups.com...
I apologize in advance if this question appears dumb as I warn that I
am not a physicist. I am a big fan of Physics and I have great interest
and enthusiasm to learn all I can about it. This question is regarding
computers - quantum and classical to be exact.
I am confused... what is the distiction between a classical computer
and a quantum computer? Correct me if I am mistaken but, isn't a
classical computer still a quantum-mechanical device? I mean, if I
don't recall incorrectly from my college Physics (I was very good at
it), computer components at the foundation level are described using
Quantum Mechanics - electron flow through semiconductors, junctions,
interferance, etc. Therefore, by its very nature, a classical computer
depends on many quantum mechanical processes, just as a Quantum
Computer does. If this is the case, what is, then, the purpose of a
Quantum Computer?
I think from a physical point you are right
but from a logical (mathematical) point you are "wrong" (in brackets).
The Classical Computer (Digital Computer) is based on binary logic.
The Quantum Computer is based on quantum logic.
The basic building block is a Flip Flop which is either in the logical state
0 or 1.
(i.e. Binary logic and bits)
From a physical point of view a Flip Flop can also be in a in-between state
(or undecided state). To solve that a Classical Computer uses clock pulses
in order to synchronise.
First this means you can only read the state of a CComputer
(that means the system is stable) when there is a clock pulse.
Secondly this means also that in order to solve a complete problem
(and find the answer on your problem) you need many clock pulses.
(At least as many clock pulses as steps in your program)
A QC uses quantum logic and quantum bits.
Quantum bits use the concept of superposition and entanglement.
In short this means when you have many quantum bits the whole system is not
in one specific state but in many states at once.
This means that in order to find the answer on your problem you only have
stop and or to perform one read operation in order to find the answer
on your problem (in theory)
To find out more do a google-search with quantum computers:
http://www.google.be/search?hl=nl&q=Quantum+Computers&meta=
(25.600.000 matches !)
If you ask me will it be possible to build a Quantum Computer which
is solely capable to solve a realistic problem the answer is no.
(count the number of prime numbers between 0 and 1023)
One of the problems is that each problem requires its own QC
with its own build logic.
There exists nothing like a general purpose QC which can solve
many problem.
A similar problem exists with Analog Computers or AC
With an AC you need a patchboard to make the connections
between the different hardware components
(Integrators, summers etc)
A second problem is that the larger the problem the more
hardware is required. (the number of Qbits etc)
Nicolaas Vroom
http://users.pandora.be/nicvroom/
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| User: "Sci-Fidelity" |
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| Title: Re: Quantum Computers and Classical Computers |
23 Sep 2006 09:27:45 AM |
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wrote:
I apologize in advance if this question appears dumb as I warn that I
am not a physicist. I am a big fan of Physics and I have great interest
and enthusiasm to learn all I can about it. This question is regarding
computers - quantum and classical to be exact.
I am confused... what is the distiction between a classical computer
and a quantum computer? Correct me if I am mistaken but, isn't a
classical computer still a quantum-mechanical device? I mean, if I
don't recall incorrectly from my college Physics (I was very good at
it), computer components at the foundation level are described using
Quantum Mechanics - electron flow through semiconductors, junctions,
interferance, etc. Therefore, by its very nature, a classical computer
depends on many quantum mechanical processes, just as a Quantum
Computer does. If this is the case, what is, then, the purpose of a
Quantum Computer?
Some problems scale much faster than the hardware required required to
solve them. QCs were supposed to scale the hardware more linearly with
these problems. The original lure was massive parallelism on a platform
suitable for implementing certain non-deterministic algorithms.
But alot of QC research seems to detour into improvements
for classical computers like higher density disk drives,
cooler CPUs, and faster, more secure and higher bandwidth
communications. This makes classical computers more powerful
and allows them to solve many problems which were not practically
solvable before.
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Quantum Computers and Classical Computers |
24 Sep 2006 03:55:38 PM |
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wrote:
I am confused... what is the distiction between a classical computer
and a quantum computer? Correct me if I am mistaken but, isn't a
classical computer still a quantum-mechanical device?
"Quantum" is being used here in the sense of "non-classical", i.e. behaving
in a way that isn't predicted even approximately by classical physics.
Ordinary computers are certainly quantum, but they're designed on classical
principles: you could build a scale model of a Pentium 4 using mechanical
relays, and it would be very large and very slow but it would still work.
Quantum computers are built from things like entangled spin systems that
have no classical analogue. You can simulate them classically, but the
simulator doesn't physically resemble the thing being simulated.
-- Ben
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| User: "" |
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| Title: Re: Quantum Computers and Classical Computers |
24 Sep 2006 05:05:22 PM |
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In article <ef6rcq$2l9$1@gemini.csx.cam.ac.uk>, Ben Rudiak-Gould <br276deleteme@cam.ac.uk> writes:
ekcientifico77@yahoo.com wrote:
I am confused... what is the distiction between a classical computer
and a quantum computer? Correct me if I am mistaken but, isn't a
classical computer still a quantum-mechanical device?
"Quantum" is being used here in the sense of "non-classical", i.e. behaving
in a way that isn't predicted even approximately by classical physics.
Ordinary computers are certainly quantum, but they're designed on classical
principles: you could build a scale model of a Pentium 4 using mechanical
relays, and it would be very large and very slow but it would still work.
Quantum computers are built from things like entangled spin systems that
have no classical analogue. You can simulate them classically, but the
simulator doesn't physically resemble the thing being simulated.
I would phrase it slightly differently. Ordinary computers are *not*
"quantum" in any reasonable sense of the word. Sure, the bottom level
processes that make the semiconductor elements to work are quantum
processes, but so what. The bottom level processes in the combustion
of gasoline in an internal combustion engine are also quantum
processes but that's hardly a reason to refer to an IC engine as
"quantum engine".
The "black box" level for ordinary computers is the level of logical
elements, i.e. elements that generate a given output for a set of given
inputs. How they generate it, is of no consequence to the principles
of operation, though, as you mention, it may be of interest to speed
of convenience. For an ordinary computer, quantum phenomena lie below
said "black box" level, just as is the case for the IC engine. For a
true quantum computer, on the other hand, the principles of operation
are anchored in QM, thus QM is above the black box level.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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