Single-photon non-linear optics with a quantum dot in a waveguide.

P Lodahl,E H Lee,A Javadi,J D Song,I Söllner,M Arcari,L Midolo,S Stobbe,S Mahmoodian,G Kiršanskė,T Pregnolato,S Lindskov Hansen

doi:10.1038/ncomms9655

Abstract

Strong non-linear interactions between photons enable logic operations for both classical and quantum-information technology. Unfortunately, non-linear 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 used as a giant non-linearity sensitive at the single-photon level. The non-linear 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 non-linearity 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.

Highlights

Strong non-linear interactions between photons enable logic operations for both classical and quantum-information technology
An alternative approach uses the intrinsic non-linearity of a quantum emitter deterministically coupled to a single photonic mode (a ‘one-dimensional (1D)atom’); such a coupling was recently achieved with single quantum dots in photonic-crystal waveguides[18]
A quantum dot in a photonic waveguide is a attractive approach to quantum non-linear optics since it can be naturally incorporated in integrated photonic circuits

Summary

Introduction

Strong non-linear interactions between photons enable logic operations for both classical and quantum-information technology. The access to an efficient optical non-linearity enables the processing of quantum information stored in light and generation of exotic states of light[1,2,3,4,5]. A non-linearity capable of operating down to the ultimate level of single photons has been long sought after, as it opens new avenues for photonic quantum-information architectures[6,7], and enables efficient Bell-state analysers[8] and single-photon transistors[9].

Results

Conclusion