The quantum cryptography studies the confidentiality of the information about the quantum mechanics by coding the information about photons. It offers a solution to the problem of distribution of keys for crypto symmetric systems. However, most of the studies until now use only two participants. In this paper, while aiming network applications, we target the quantum cryptography with continuous variables for states of Fock of several photons (two or four) resulting from few users. The probability aspect of the world of quanta incites us to choose a law of probability and a universe of the possible values to present these states. Indeed, the mathematical representation of the quantun continuous variables is initially made by functions of wave [1]. The passage throw the space of phases allowed the introduction of the quasi-probabilities of Wigner which can take negative values for the states of Pock. A work presented during this article is to choose an outline of positive values of this distribution so that it is a probability that allows a more precise study of a chain of quantum communication.

C. Karaborni

Papers

Function of wigner of the states of fock of several photons: choice of outlines in the space of the phases