Probabilities, Tensors and Qubits

In the paper is discussed complete probabilistic description of quantum systems with application to multiqubit quantum computations. In simplest case it is a set of probabilities of transitions to some fixed set of states. The probabilities in the set may be represented linearly via coefficients of density matrix and it is very similar with description using mixed states, but also may give some alternative view on specific properties of quantum circuits due to possibility of direct comparison with classical statistical paradigm.Comment: 15 pages, "QIS preprint" layou

Comment on ``Quantum noise influencing human behaviour could fake effectiveness of drugs in clinical trials''

Here are discussed some problems concerning quant-ph/0208006.Comment: 10 pages, 3 eps figures, 12pt LaTeX

Programmable Quantum State Transfer

A programmable quantum networks model is used in this paper for development of methods of control of a quantum state transport. These methods may be applied for a wide variety of patterns of controlled state transmission and spreading in quantum systems. The programmable perfect state transfer and quantum walk, mobile quantum (ro)bots and lattice gas automata may be described by unified way with such approach.Comment: 4+ pages, 2 columns, revtex4; v2 some clarification, couple new examples and reference

Nondeterministic Recursion with Quantum Units (I-V)

In this paper are discussed some formal properties of quantum devices necessary for implementation of nondeterministic Turing machine.Comment: LaTeX, 5 page

Towards Lagrangian approach to quantum computations (revised)

In this work is discussed possibility and actuality of Lagrangian approach to quantum computations. Finite-dimensional Hilbert spaces used in this area provide some challenge for such consideration. The model discussed here can be considered as an analogue of Weyl quantization of field theory via path integral in L. D. Faddeev's approach. Weyl quantization is possible to use also in finite-dimensional case, and some formulas may be simply rewritten with change of integrals to finite sums. On the other hand, there are specific difficulties relevant to finite case.Comment: LaTeX 9 pages; v2, v3: minor corrections; v4: more significant revisio

On Quantum Cellular Automata

In recent work [quant-ph/0405174] by Schumacher and Werner was discussed an abstract algebraic approach to a model of reversible quantum cellular automata (CA) on a lattice. It was used special model of CA based on partitioning scheme and so there is a question about quantum CA derived from more general, standard model of classical CA. In present work is considered an approach to definition of a scheme with "history", valid for quantization both irreversible and reversible classical CA directly using local transition rules. It is used language of vectors in Hilbert spaces instead of C*-algebras, but results may be compared in some cases. Finally, the quantum lattice gases, quantum walk and "bots" are also discussed briefly.Comment: LaTeX (amsmath, amssymb, graphicx packages) 17 pages, 22 eps figures; v2: misspelling corrected, +2 figure

ReveR: Software Simulator of Reversible Processor with Stack

A software model of a reversible processor ReveR with the stack is discussed in this paper. An architecture, the minimal set of elementary reversible operations together with an implementation of the basic control flow structures and procedures calls using simple assembler language are described.Comment: LaTeX, 7 pages, no figures, 3 tables, v2: spelling and grammar corrected; project url http://friedmann.objectis.net/Members/vlasov/reve

Comment on "How the No-Cloning Theorem Got its Name"

A review by A. Peres [quant-ph/0205076] appears recently. It is difficult to add something to such kind of fundamental themes, but here is briefly presented some ideas about challenges of the no-cloning theorem and imaginary modifications of quantum mechanics, that could make precise cloning possible.Comment: 3 pages, 2 col., LaTeX 2

Comment on ``Quantization of Diffeomorphism-Invariant Theories with Fermions''

In the comment to the article by J.Baez and K.Krasnov (hep-th/9703112) are discussed some topics related with application of certain constructions to non-trivial principal bundles.Comment: 5 pages LaTe

Symmetries of complexified space-time and algebraic structures in quantum theory

In this paper is discussed description of some algebraic structures in quantum theory by using formal recursive constructions with "complex Poincar\'e group" ISO(4,C).Comment: v2. style change: REVTeX, 12 pg, preprint, draft, minor correction