  We theoretically demonstrate dynamically selective bidirectional emission and
absorption of a single itinerant microwave photon in a waveguide. The proposed
device is an artificial molecule composed of two qubits coupled to a waveguide
a quarter-wavelength apart. By using simulations based on the input--output
theory, we show that upon preparing an appropriate entangled state of the two
qubits, a photon is emitted directionally as a result of the destructive
interference occurring either at the right or left of the qubits. Moreover, we
demonstrate that this artificial molecule possesses the capability of absorbing
and transmitting an incoming photon on-demand, a feature essential to the
creation of a fully inter-connected one-dimensional quantum network, in which
quantum information can be exchanged between any two given nodes.
