EN
By using the notion of contraction of Lie groups, we transfer $L^{p} - L²$ estimates for joint spectral projectors from the unit complex sphere $S^{2n+1}$ in $ℂ^{n+1}$ to the reduced Heisenberg group hⁿ. In particular, we deduce some estimates recently obtained by H. Koch and F. Ricci on hⁿ. As a consequence, we prove, in the spirit of Sogge's work, a discrete restriction theorem for the sub-Laplacian L on hⁿ.