  Routing plays an important role in programming noisy, intermediate-scale
quantum (NISQ) devices, where limited connectivity in the register is overcome
by swapping quantum information between locations. However, routing a quantum
state using noisy gates introduces non-trivial noise dynamics and deciding on
an optimal route to minimize accumulated error depends on estimates for the
expected state fidelity. Here we verify the presence of state-dependent routing
dynamics in a NISQ processor using tomographic characterization of routed state
fidelity. We develop a composable, state-dependent noise model for the
underlying channel, which is characterized efficiently using pair-wise
experimental measurements. We compare these model predictions for the fidelity
against the tomographic state reconstructions recovered from the quantum
device. These results validate the utility of state-dependent noise models for
guiding near-real time routing decisions using efficient characterizations of
NISQ devices.
