# Giant non-linear interaction between two optical beams via a quantum dot embeddedin a photonic wire

## TL;DR

This paper demonstrates a giant optical non-linearity at the single-photon level using a quantum dot in a photonic wire, enabling control of one laser beam's reflectivity by another with very few photons, promising for quantum optical devices.

## Contribution

It introduces a novel two-mode non-linearity in a semiconductor quantum dot system, achieving control at the single-photon level with broad bandwidth and high efficiency.

## Key findings

- Achieved control of laser reflectivity with as few as 10 photons per QD lifetime.
- Demonstrated a two-mode giant non-linearity in a semiconductor quantum dot system.
- Discussed potential applications in ultra-low power optical and quantum gates.

## Abstract

Optical non-linearities usually appear for large intensities, but discrete transitions allow for giant non-linearities operating at the single photon level. This has been demonstrated in the last decade for a single optical mode with cold atomic gases, or single two-level systems coupled to light via a tailored photonic environment. Here we demonstrate a two-modes giant non-linearity by using a three-level structure in a single semiconductor quantum dot (QD) embedded in a photonic wire antenna. The large coupling efficiency and the broad operation bandwidth of the photonic wire enable us to have two different laser beams interacting with the QD in order to control the reflectivity of a laser beam with the other one using as few as 10 photons per QD lifetime. We discuss the possibilities offered by this easily integrable system for ultra-low power logical gates and optical quantum gates.