christophe delriviere writes:
>
> you used the term "computronium" for optimized computational matters, i
> find it a nice one... did you coined it or does it appear in some book
> or sci-fi litterature, culture ?
N. Margolus, "Crystalline Computation', to appear in The Feynman Lectures on Computation, volume 2 (Anthony Hey, ed.), Addison-Wesley (1998). Preprint (46 pages; .ps.gz) on the web.
[...]
Thus in the distant future I expect that our most powerful large-scale
general purpose computers will be built out of macroscopic crystalline
arrays of identical invertible computing elements. We would make such
large arrays out of identical elements because they will then be
easier to control, to design, to build and to test. These will be the
distant descendants of todays SIMD and FPGA computing devices: when we
need to perform inhomogenous computations, we will put the
irregularities into the program, not the hardware. The problem of
arranging the pieces of a computation in space will be part of the
programming effort: architectural ideas that are used today in
physical hardware may reappear as data structures within this new
digital medium. With molecular scale computing elements, a small chunk
of this computronium[63] would have more memory and processing power
^^^^^^^^^^^^
Note that I don't expect our highest performance general purpose computers to be quantum spin computers of the sort discussed in Section 1.1. In such a machine, the whole computer operates on a superposition of distinct computations simultaneously. This kind of quantum parallelism is very delicate, and the overhead associated with the difficult task of maintaining a superposition of computations over a large spatial scale will be such that it will only be worth doing in a very specialized situations -- if it is possible at all[74]. This won't be something that we will do in our general purpose computers. [...]
[63] Margolus, N., "Fundamental physical constraints on the computational process", Nanotechnology: Research and Perspectives (B.C. Crandall and J. Lewis eds.), MIT Press (1992).
[74] Preskill, J. "Fault-tolerant quantum computation", in [54] and quant-ph/9712048 ( http://xxx.lanl.gov )