We report on a quantum interface linking a diamond NV center quantum network node and 795nm photonic time-bin qubits compatible with Thulium and Rubidium quantum memories. The interface makes use of two-stage low-noise quantum frequency conversion and waveform shaping to match temporal and spectral photon profiles. Two-photon quantum interference shows high indistinguishability between converted 795nm photons and the native NV center photons. We use the interface to demonstrate quantum teleportation including real-time feedforward from an unbiased set of 795nm photonic qubit input states to the NV center spin qubit, achieving a teleportation fidelity well above the classical bound. This proof-of-concept experiment shows the feasibility of interconnecting different quantum network hardware.@en

The creation of well-understood structures using spectral hole burning is an important task in the use of technologies based on rare-earth ion-doped crystals. We apply a series of different techniques to model and improve the frequency dependent population change in the atomic level structure of thulium yttrium gallium garnet (Tm:YGG). In particular we demonstrate that, at zero applied magnetic field, numerical solutions to frequency-dependent three-level rate equations show good agreement with spectral hole-burning results. This allows us to predict spectral structures given a specific hole-burning sequence, the underpinning spectroscopic material properties, and the relevant laser parameters. This enables us to largely eliminate power-dependent hole broadening through the use of adiabatic hole-burning pulses. Although this system of rate equations shows good agreement at zero field, the addition of a magnetic field results in unexpected spectral diffusion proportional to the induced Tm ion magnetic-dipole moment and average magnetic-field strength, which, through the quadratic Zeeman effect, dominates the optical spectrum over long timescales. Our results allow optimization of the preparation process for spectral structures in a large variety of rare-earth ion-doped materials for quantum memories and other applications.

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