  Loading quantum information deterministically onto a quantum node is an
important step towards a quantum network. Here, we demonstrate that
coherent-state microwave photons, with an optimal temporal waveform, can be
efficiently loaded onto a single superconducting artificial atom in a
semi-infinite one-dimensional (1D) transmission-line waveguide. Using a weak
coherent state (average photon number N<<1 with an exponentially rising
waveform, whose time constant matches the decoherence time of the artificial
atom, we demonstrate a loading efficiency of above 94% from 1D semi-free space
to the artificial atom. We also show that Fock-state microwave photons can be
deterministically loaded with an efficiency of 98.5%. We further manipulate the
phase of the coherent state exciting the atom, enabling coherent control of the
loading process. Our results open up promising applications in realizing
quantum networks based on waveguide quantum electrodynamics (QED).
