  Using electrical detection of a strongly coupled spin-photon system comprised
of a microwave cavity mode and two magnetic samples, we demonstrate the long
distance manipulation of spin currents. This distant control is not limited by
the spin diffusion length, instead depending on the interplay between the local
and global properties of the coupled system, enabling systematic spin current
control over large distance scales (several centimeters in this work). This
flexibility opens the door to improved spin current generation and manipulation
for cavity spintronic devices.
