Optical nonlinearity for few-photon pulses on a quantum dot-pillar   cavity device
  Giant optical nonlinearity is observed under both continuous-wave and pulsed excitation in a deterministically-coupled quantum dot-micropillar system, in a pronounced strong-coupling regime. Using absolute reflectivity measurements we determine the critical intracavity photon number as well as the input and output coupling efficiencies of the device. Thanks to a near-unity input-coupling efficiency, we demonstrate a record nonlinearity threshold of only 8 incident photons per pulse. The output-coupling efficiency is found to strongly influence this nonlinearity threshold. We show how the fundamental limit of single-photon nonlinearity can be attained in realistic devices, which would provide an effective interaction between two coincident single photons. 
Vivien Loo, Christophe Arnold, Olivier Gazzano, Aristide Lemaitre,   Isabelle Sagnes, Olivier Krebs, Paul Voisin, Pascale Se...
physics.optics cond-mat.mes-hall quant-ph