  The ever-evolving demands for computational power and for a securely
connected world dictate the development of quantum networks where entanglement
is distributed between connected parties. Solid-state quantum emitters in the
telecom C-band are a promising platform for quantum communication applications
due to the minimal absorption of photons at these wavelengths, "on-demand"
generation of single photon flying qubits, and ease of integration with
existing network infrastructure. Here, we use an InAs/InP quantum dot to
implement an optically active spin-qubit, based on a negatively charged exciton
where the electron spin degeneracy is lifted using a Voigt magnetic field. We
investigate the coherent interactions of the spin-qubit system under resonant
excitation, demonstrating high fidelity spin initialisation and coherent
control using picosecond pulses. We further use these tools to measure the
coherence of a single, undisturbed electron spin in our system. Finally, we
report the first demonstration of spin-photon entanglement in a solid-state
system capable of direct emission into the telecom C-band.
