# Operations on NV center qubits

One of the options to make qubits is by using Nitrogen-Vacancy (NV) centers in diamond. These defects have an electron spin that can be used for many quantum applications, especially since these electron spins are relatively easy to link to other NV centers. But how does this work?

In this video, we cover this important aspect of NV centers in diamond. Group leader at QuTech Tim Taminiau first explains how our complete control over the electron spin gives us access to control over more qubits (nuclear spins) surrounding an NV center. After that, he explains how we generate quantum entanglement between two nodes consisting of NV centers in diamond.

## Prerequisite knowledge

- The basics of NV centers
- What are two-qubit gates (CNOT)
- Entanglement

## Further Thinking

Suppose you can change anything you want around an NV center, how would you set-up your environment such that you maximize your control over the nuclear spins surrounding an NV center? Think, for example, about the geometric position of the spins!

## Further reading

There are many papers to read about NV centers in diamond. Most of the papers are quite technical, but very interesting to read nonetheless. Give it a go!

This review article by F. Jelezko & J. Wrachtrup gives an expert introduction for defects in diamond (of which the NV is one version).

Here a research group from Delft demonstrates an entangled link between two NV nodes that are roughly 1.3 km apart.

- https://arxiv.org/abs/1603.05705 (Hensen et al., 2015)

The group of Tim Taminiau (the lecturer in this video) is doing much research on using nuclear spins around such an NV center. Two recent publications are

- https://arxiv.org/abs/1905.02094 (Bradley et al., 2019), where they use 10 nuclear spins to build a quantum register and perform an actual quantum algorithm.
- https://arxiv.org/abs/1905.02095 (Abobeih et al., 2019). Here the group demonstrates another application for NV centers in diamond: quantum sensing. By using a complex sequence, they can locate the position (x,y,z-coordinate, that is) of 27 nuclear spins around the NV center with sub-angstrom precision (less than 0.1 nm)!