ua nt - p h / 01 02 02 9 v 1 5 F eb 2 00 1 Entangling capacity of global phases and implications for Deutsch - Jozsa algorithm

ua nt - p h / 01 02 02 5 v 1 5 F eb 2 00 1 Teleportation with indistinguishable particles . ∗

We analyze in a critical way the mathematical treatment of a quantum teleportation experiment performed with photon particles, showing that a symmetrization operation over both the polarization and spatial degrees of freedom of all the particles involved is necessary in order to reproduce correctly the observed experimental data.

ua nt - p h / 02 02 03 0 v 1 5 F eb 2 00 2 Quantum Computer with Fixed Interaction is Universal

It is proved that a quantum computer with fixed and permanent interaction of diagonal type between qubits proposed in the work quant-ph/0201132 is universal. Such computer is controlled only by one-qubit quick transformations, and this makes it feasible.

ua nt - p h / 01 01 02 8 v 1 5 J an 2 00 1 QUANTUM LOGICS

ar X iv : q ua nt - p h / 98 02 04 9 v 3 30 S ep 1 99 8 Quantum Lower

We examine the number T of queries that a quantum network requires to compute several Boolean functions on {0, 1}N in the black-box model. We show that, in the blackbox model, the exponential quantum speed-up obtained for partial functions (i.e. problems involving a promise on the input) by Deutsch and Jozsa and by Simon cannot be obtained for any total function: if a quantum algorithm computes...

nt - p h / 01 02 03 8 v 1 6 F eb 2 00 1 Quasiprobability and Probability Distributions for Spin 1 / 2 States ∗

We develop a Radon like transformation, in which P quasiprobability distribution for spin 1/2 states is written in terms of the tomographic probability distribution w.