Quantum information science and M-theory

Boris Leykin

Hello.
I've got childish question.
I know that quantum computers are more effective than classical ones
in solving some problems. Naturally, a thought have come to me: are
there computers which are more effective than quantum ones, maybe
some "Superstring" computers? And maybe there are computers which
are more effective than Superstring computers? And so foth, ad infinitum.

I tried to search on the Internet for "superstring computers" with no result.
Accidentally on the site of John Preskill
I've found a talk on "quantum computation and the future of physics".
Here are Preskill's words from this talk:
"Can a quantum computer simulate M theory efficiently? Perhaps not,
because of M-theory inherent nonlocality. E.g., a quantum system
described by M-theory may have no natural tensor product
decomposition into smaller systems. Thus, M-theory may be a more
powerful computational model."

So I decided to ask you, what do you think about all this?

f-h

I remember that somebody did point out that some String theory models are computationally ridiculously powerful.
Anybody remember which paper that was, or remembers something else that might be a lead to finding it?

Boris Leykin

Hi :)
I peeped in to ask what is the progress?

Oh! Why it is so difficult to invent "string" computer I can't understand

Here Andrew Steane says:

"7.1 Simulation of physical systems

The first and most obvious application of a QC is that
of simulating some other quantum system. To simulate
a state vector in a 2^n-dimensional Hilbert space, a clas-
sical computer needs to manipulate vectors containing
of order 2^n complex numbers, whereas a quantum com-
puter requires just n qubits, making it much more effi-
cient in storage space. To simulate evolution,in general
both the classical and quantum computers will be inef-
ficient. A classical computer must manipulate matrices
containing of order 2^(2n) elements, which requires a num-
ber of operations (multiplication, addition) exponen-
tially large in n, while a quantum computer must build
unitary operations in 2^n-dimensional Hilbert space,
which usually requires an exponentially large num-
ber of elementary quantum logic gates. Therefore the
quantum computer is not guaranteed to simulate every
physical system efficiently. However, it can be shown
that it can simulate a large class of quantum systems
efficiently, including many for which there is no effi-
cient classical algorithm, such as many-body systems
with local interactions."

"To simulate evolution,in general both the classical and quantum computers will be inefficient."
Does he mean that "string" computers really exist?
"Therefore the quantum computer is not guaranteed to simulate every physical system efficiently."
Don't you know what are those systems? Can you give an example of one such system, please?

ZapperZ

This thread is getting to be too highly-speculative, even for this particular forum.

Please note that the reason why we can talk about "quantum computers" is because it is based on a well-established theory that has been verified to no end. That is how we can make applications out of something. We cannot make applications out of something that is still unverified and not understood. Not only that, there isn't JUST ONE string/superstring theory.

Please re-read the PF Guidelines that you have agreed to, especially on overly-speculative post. This thread is done.

Zz.

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