  We consider symmetric operators of the form $S := A\otimes I_{\mathfrak T} +
I_{\mathfrak H} \otimes T$ where $A$ is symmetric and $T = T^*$ is (in general)
unbounded. Such operators naturally arise in problems of simulating point
contacts to reservoirs. We construct a boundary triplet $\Pi_S$ for $S^*$
preserving the tensor structure. The corresponding $\gamma$-field and Weyl
function are expressed by means of the $\gamma$-field and Weyl function
corresponding to the boundary triplet $\Pi_A$ for $A^*$ and the spectral
measure of $T$. Applications to 1-D Schr\"odinger and Dirac operators are
given. A model of electron transport through a quantum dot assisted by cavity
photons is proposed. In this model the boundary operator is chosen to be the
well-known Jaynes-Cumming operator which is regarded as the Hamiltonian of the
quantum dot.
