We report on the realization and verification of quantum entanglement between a nitrogen-vacancy electron spin qubit and a telecom-band photonic qubit. First we generate entanglement between the spin qubit and a 637 nm photonic time-bin qubit, followed by photonic quantum frequency conversion that transfers the entanglement to a 1588 nm photon. We characterize the resulting state by correlation measurements in different bases and find a lower bound to the Bell state fidelity of ≥0.77±0.03. This result presents an important step towards extending quantum networks via optical fiber infrastructure.@en

Here, we discuss our experimental efforts toward building an alignment-free, long-lived, and efficient cavity-enhanced quantum memory in a thulium-doped crystal. A significant step forward for creating efficient quantum memories with long optical storage times.@en

Here, we discuss our experimental efforts toward building an alignment-free, long-lived, and efficient cavity-enhanced quantum memory in a thulium-doped crystal. A significant step forward for creating efficient quantum memories with long optical storage times.@en

We experimentally demonstrate the preservation of entanglement between an NV spin and a photon upon quantum frequency conversion to the Telecom band. This is a crucial step in realizing long-distance quantum networks.@en