Electrically tunable, two-photon interference from remote silicon-vacancy centers in industrial silicon carbide

Abstract

Distributed quantum networks rely on spatially separated, independently operated quantum systems as network nodes, whose emitted photons must be interfered with high visibility to establish end-to-end entanglement. Crucially, for network-relevant applications, high visibilities must be achieved over prolonged timescales to reduce overheads for error correction, and to increase network rates. Here, we demonstrate experimentally that silicon vacancy $\mathrm{V_{Si}}$ color centers in silicon carbide (SiC) achieve these requirements, notably in a mass-deployable fashion. We integrate $\mathrm{V_{Si}}$ centers in different industrial-grade SiC p-i-n diodes, which are controlled via voltage biassing. This way, we demonstrate both, spectral overlapping of 19 randomly selected $\mathrm{V_{Si}}$ centers in different diodes, as well as spectral narrowing close to the lifetime limit, i.e., typically below 60 MHz. Notably, these performance parameters are long-term stable, e.g., readjusting the p-i-n diode bias is required only every 8.4 hours, which reduces significantly the overall experimental overhead. We then use these assets to demonstrate high-quality two-photon interference between $\mathrm{V_{Si}}$ centers located in two different cryostat setups, which are spatially separated by two meters. Notably, we perform a 26-days long measurement campaign, demonstrating two-photon interference with state-of-the-art raw interference visibilities of 82%, which aligns with the current state-of-the-art. These results establish $\mathrm{V_{Si}}$ centers in industry-grade SiC devices as a scalable, spectrally stable building block for distributed quantum networks.