Spectrally reconfigurable tin-vacancy centers for remote two-photon interference

Scalable quantum networks rely on optical links between long-lived qubits to distribute entanglement. Tin-vacancy ( SnV − ) centers in diamond combine long spin coherence at liquid-helium temperatures with highly coherent, spin-dependent optical transitions, making them promising network qubits. Connecting independent centers, however, requires indistinguishable photons: solid-state inhomogeneity creates frequency mismatch, while inversion symmetry suppresses the first-order electrical response. Here, we establish optical connectivity between two remote SnV − centers in separate cryogenic nodes. Using local electrodes, we tune the optical transition by up to 4 GHz via the Stark effect while maintaining optical coherence. Bringing the two transitions into resonance yields remote Hong-Ou-Mandel interference with a measured zero-delay visibility of 80 ( 6 ) % without postprocessing. The same electrodes provide dynamic spectral control, producing resolved Floquet sidebands at drive frequencies up to 1.5    GHz . These results establish a locally reconfigurable optical interface for connecting remote SnV − quantum-network nodes.