Coupled defect centers for diamond quantum nodes*

Nitrogen-vacancy (NV) defect centers in diamond are well-suited to realize quantum networks owing to a coherent spin ground state, nuclear quantum memories and an optical transition for remote entanglement. State-of-the-art experiments with single NV centers used ¹³C atoms as quantum memories to perform entanglement distillation and quantum error correction [Kalb et. al., Science, 2017, Cramer et al., Nat. Commun., 2015]. Such experiments involve an intrinsic trade-off: reducing the coupling to the NV center improves ¹³C quantum memories, but reduces gate speeds.

In this work, we aim to extend the possibilities of quantum networks by creating systems of two or more coupled defects centers in diamond. Such coupled defects, hold the promise to combine fast gates with well-isolated quantum nuclear memories. I will present recent progress towards this goal.

First, we realized a long coherence time, exceeding two seconds, of the host nitrogen spin of a single NV center, demonstrating its potential as a quantum memory. Second, I will discuss our recent progress using ion implantation and other techniques to realize coupled defects.