Full two-photon downconversion of just a single photon

TL;DR

This paper demonstrates the theoretical possibility of converting a single photon into two photons with over 99% efficiency using waveguide QED systems, including realistic loss considerations and potential circuit QED implementations.

Contribution

It provides a detailed analysis and numerical validation of single-photon to two-photon downconversion in waveguide QED, proposing a near-perfect efficiency method with practical implementation strategies.

Findings

Over 99% downconversion efficiency achievable

Inclusion of realistic losses in the model

Feasible implementation in circuit QED with transmons

Abstract

We demonstrate, both numerically and analytically, that it is possible to generate two photons from one and only one photon. We characterize the output two photon field and make our calculations close to reality by including losses. Our proposal relies on real or artificial three-level atoms with a cyclic transition strongly coupled to a one-dimensional waveguide. We show that close to perfect downconversion with efficiency over 99% is reachable using state-of-the-art Waveguide QED architectures such as photonic crystals or superconducting circuits. In particular, we sketch an implementation in circuit QED, where the three level atom is a transmon.