Loophole-free Bell test

Back in 2015, the group of professor Hanson from QuTech managed to prove entanglement by proving the Bell inequality. Read more about this here:
Paper on Loophole-free Bell testhttps://www.nature.com/articles/nature15759

New: Entanglement on demand!

Scientists from Delft managed to create superposition faster than it would decohere, allowing deterministic entanglement.
Paper on entanglement on demand

Or look at this video!
Video on entanglement on demand

In the figure, you can see the so-called bandgap diagram of an NV center. The y-axis represents energy and the horizontal lines are the energy states. Each electron is represented by an up- or down-arrow.

In this particular bandgap diagram you can see six trapped electrons. This sixth electron is added by excitation of one of the initially trapped electrons from the valence band to a higher energy state. This vacancy is easily filled up with one of the many electrons present in the valence band.

This new system, with 6 trapped electrons is called the NV minus state.