Reply to Pedro Marijuan Dear Pedro, a). Bilogical information and QI. I really like your analogy between BI and QI, especially remark on \"some brief biological windows\" in which biological computing is possible. In the same way we have \"some brief quantum windows\" in that quantum computing is possible. In April I had a course of lectures at Institute of Physical Technologies of Russian Academy of Sc. There is a strong group which works on quantum computers with ion-registers. They pointed out to tremendous difficulty in creation of long strings of ion-registers. Difficulties icreases essentially nonlinear with increasing of the number of ions. Strings of ions become very unstable. And \"brief quantum windows\" are too brief to perform a quantum computational cycle. On the other hand, in QM such composed systems are described very well by tensor products of Hilbert spaces. During an informal conversation experimenters even presented doubts that everything is okey with QM-description or at least our understanding of it.
b). Not so many quantum algorithms. There is some analogy with Analogous Computers. Such a physical divice is constructed for solution of one of a restricted class of problems. Problems from teh corresponding class can be solved essentially quicker than by digital computers. An Analogous Computer works directly with physical information without it digitalization. Are quantum computers special Analogous Computers? In some sense yes. Therefore it is not so surprising that we can solve only very special problems. But of course, such an analogy might be totally wrong. Reply to Michael Devereux: a) Conference proceedings of Vaxjo conferences, see about these conferences at http://www.vxu.se/msi/aktuellt/konferens/index.xml can be received without any charge if you send me Email, with subject Proceedings and your post-address (except the last two years, since American Institute of Physics started to publish the proceedings of our series of conferences). b). Interpretation of wave function. Michael: \"Im convinced that Born got the interpretation of the wavefunction correct. Quantum theory, as you emphasize, Andrei, is fundamentally about probability - the probable result of the next measurement. One mistake, and an almost ineradicable source of confusion, is the misunderstanding that the wavefunction, Psi, can also always be the present state of the physical system. One can cite real examples where both interpretations are not possibly valid simultaneously.Ive traced the mistaken notion that Psi is always the state of the system as far back as Bohms book on quantum mechanics. (Does anyone know an earlier source?) He certainly doesnt even attempt a proof, merely citing some special cases.\" Dear Michael, I agree with you that interpretation of wave function is the basic problem of QM. The presence of numerous interpreation and the impossibility to choose one of them (\"to prove\" that this one is correct and all others are not) expresses the deepest crises in physics. \"The wavefunction, Psi, can also always be the present state of the physical system.\" -- This is nothing else than the conventional Copenhagen interpretation of wave function -- Bohr and Heisenberg, von Neumann, Pauli,... The story was very complicated. They chosen such an interpretation not with the great pleasure. There was a lot of doubts. Personally I completely agree with you. I do not think that the Psi-function can be always considered as the state of e.g. individual electron. For stationary states - yes, but nonstationary? With Best Regards, Andrei Khrennikov Director of International Center for Mathematical Modeling in Physics, Engineering, Economy and Cognitive Sc., University of Vaxjo, Sweden _______________________________________________ fis mailing list fis@listas.unizar.es http://webmail.unizar.es/mailman/listinfo/fis