On the tomographic picture of quantum mechanics

4 pages, no figures.-- PACS codes: 03.65 Sq; 03.65.Wj.-- ArXiv pre-print available at: http://arxiv.org/abs/1004.0102We formulate necessary and sufficient conditions for a symplectic tomogram of a quantum state to determine the density state. We establish a connection between the (re)construction by means of symplectic tomograms with the construction by means of Naimark positive definite functions on the Weyl-Heisenberg group. This connection is used to formulate properties which guarantee that tomographic probabilities describe quantum states in the probability representation of quantum mechanics.This work was partially supported by MTM2007-62478 Research project, Ministry of Science, Spain