The spin of a carrier in a quantum dot is an attractive solid-state quantum bit to store the quantum information.  The spin coherence time of an electron or a hole can reach values in the 0.1-1 µs range when it takes typically hundred picoseconds to manipulate a spin.
This coherence to manipulation time ratio above one thousand is highly promising for quantum computation.

To benefit from this possibility, we develop efficient spin-photon interfaces to make sure that every photon sent on the device interacts with a single spin.
We have recently demonstrated that a single spin in a micropillar cavity can rotate the polarization of a photon by +-6°, depending on the spin state.

Such efficient spin-photon interfaces are the backbone for the demonstration of photon deterministic gates, overcoming a strong limitation of today’s optical quantum technologies coming from the probabilistic operations of the gates.

Further reading: “Macroscopic rotation of polarization induced by a single spin“