Strong nonlinear interactions between photons enable logic operations for both classical and quantum-information technology. Unfortunately, nonlinear interactions are usually feeble and therefore all-optical logic gates tend to be inefficient. A quantum emitter deterministically coupled to a propagating mode fundamentally changes the situation, since each photon inevitably interacts with the emitter, and highly correlated many-photon states may be created . Here we show that a single quantum dot in a photonic-crystal waveguide can be utilized as a giant nonlinearity sensitive at the single-photon level. The nonlinear response is revealed from the intensity and quantum statistics of the scattered photons, and contains contributions from an entangled photon-photon bound state. The quantum nonlinearity will find immediate applications for deterministic Bell-state measurements and single-photon transistors and paves the way to scalable waveguide-based photonic quantum-computing architectures.
@article{arxiv.1504.06895,
title = {Single-photon nonlinear optics with a quantum dot in a waveguide},
author = {A. Javadi and I. Söllner and M. Arcari and S. L. Hansen and L. Midolo and S. Mahmoodian and G. Kiršanskė and T. Pregnolato and E. H. Lee and J. D. Song and S. Stobbe and P. Lodahl},
journal= {arXiv preprint arXiv:1504.06895},
year = {2019}
}