The tin-vacancy center in diamond as a quantum memory node at 4 K*

Optically interfaced solid-state spins are amongst the most promising candidates for quantum networking devices, combining an efficient spin-photon interface with a local nuclear quantum register. Amongst the Group-IV color centers in diamond with their desirable optical properties, the negatively charged tin-vacancy center (SnV) is particularly interesting. Its large spin-orbit coupling offers strong protection against phonon dephasing at 1.7 K at the cost of less efficient microwave driving of the electronic spin.

 

We recently overcame this challenge by embedding SnVs in uniformly strained thin diamond membranes, allowing us to perform efficient microwave control with 99.36(9) % gate fidelity. The introduced crystal strain further increases the ground-state splitting, which sufficiently suppresses the phonon-induced decoherence at even higher temperatures. This enabled us to show coherence times of up to 223(10) µs at 4 K.

 

Here we report on the recent experimental results of implementing a quantum memory by performing multi qubit gates of the electronic spin and nearby nuclei. In addition, we show our progress of embedding the diamond membranes into open optical microcavities. Combining both, we strive to make this platform a prime candidate for scalable quantum repeaters.