  Generating high-quality multi-particle entanglement between communicating
parties is the primary resource in quantum teleportation protocols. To this
aim, we show that the natural dynamics of a single spin chain is able to
sustain the generation of two pairs of Bell states - possibly shared between a
sender and a distant receiver - which can in turn enable two-qubit
teleportation. In particular, we address a spin-1/2 chain with XX interactions,
connecting two pairs of spins located at its boundaries, playing the roles of
sender and receiver. In the regime where both end pairs are weakly coupled to
the spin chain, it is possible to generate at predefinite times a state that
has vanishing infidelity with the product state of two Bell pairs, thereby
providing nearly unit fidelity of teleportation. We also derive an effective
Hamiltonian via a second-order perturbation approach that faithfully reproduces
the dynamics of the full system.
