  High-rate remote entanglement between photon and matter-based qubits is
essential for distributed quantum information processing. A key technique to
increase the modest entangling rates of existing long-distance quantum
networking approaches is multiplexing. Here, we demonstrate a temporally
multiplexed ion-photon interface via rapid transport of a chain of nine calcium
ions across 74 $\mathrm{\mu m}$ within 86 $\mathrm{\mu s}$. The non-classical
nature of the multiplexed photons is verified by measuring the second-order
correlation function with an average value of $g^{(2)}(0)$ = 0.060(13),
indicating negligible crosstalk between the multiplexed modes. In addition, we
characterize the motional degree-of-freedom of the ion crystal after transport
and find that it is coherently excited to as much as $\bar{n}_\alpha\approx
110$ for the center-of-mass mode. Our proof-of-principle implementation paves
the way for large-scale quantum networking with trapped ions, but highlights
some challenges that must be overcome.
