Heterogeneous entanglement between a trapped ion and a solid-state quantum memory
Researchers successfully entangled a single trapped Yb+ ion with a solid-state quantum memory using polarization-maintaining quantum frequency conversion over 75 meters. The resulting entanglement showed high fidelity (89.21%) and violated the CHSH-Bell inequality by 6 standard deviations, proving nonlocality between these two different physical systems, which is a crucial step for scalable quantum networks.