filter_postA strong limitation of today’s optical quantum technologies comes from the use of linear optics for implementing logic gates. In the linear regime, the quantum gates are probabilistics, meaning that they operate as expected typically 10-25% of the times. We explore new ways to manipulate the quantum information using non-linear phenomena at the single photon level.
We use the quantum dot as a non-linear medium for which the absorption of one photon conditions the transmission of a second one.

We have demonstrated that such non-linearities can be reached at the very few photon level (n=0.2-8) and that we can fabricate devices that perform as photon filters: when a laser is sent on the device, the reflected light is 80% single photon like.

Further reading: “A solid-state single photon filter“.