  In quantum communication networks, wires represent well-defined trajectories
along which quantum systems are transmitted. In spite of this, trajectories can
be used as a quantum control to govern the order of different noisy
communication channels, and such a control has been shown to enable the
transmission of information even when quantum communication protocols through
well-defined trajectories fail. This result has motivated further
investigations on the role of the superposition of trajectories in enhancing
communication, which revealed that the use of quantum control of parallel
communication channels, or of channels in series with quantum-controlled
operations, can also lead to communication advantages. Building upon these
findings, here we experimentally and numerically compare different ways in
which two trajectories through a pair of noisy channels can be superposed. We
observe that, within the framework of quantum interferometry, the use of
channels in series with quantum-controlled operations generally yields the
largest advantages. Our results contribute to clarify the nature of these
advantages in experimental quantum-optical scenarios, and showcase the benefit
of an extension of the quantum communication paradigm in which both the
information exchanged and the trajectory of the information carriers are
quantum.
