Maximally efficient biphoton generation by single photon decay in nonlinear quantum photonic circuits

TL;DR

This paper introduces a nonperturbative formalism and a scheme for highly efficient biphoton generation via single-photon decay in nonlinear quantum photonic circuits, establishing fundamental efficiency limits.

Contribution

It generalizes the critical coupling concept to nonlinear quantum regimes and defines the maximum achievable efficiency of biphoton generation.

Findings

Efficiency approaches unity with low absorption losses

Generalized critical coupling for nonlinear photon modes

Established fundamental upper limit on generation efficiency

Abstract

We develop a general nonperturbative formalism and propose a specific scheme for maximally efficient generation of biphoton states by parametric decay of single photons. We show that the well-known critical coupling concept of integrated optics can be generalized to the nonlinear coupling of quantized photon modes to describe the nonperturbative optimal regime of a single-photon nonlinearity and establish a fundamental upper limit on the nonlinear generation efficiency of quantum-correlated photons, which approaches unity for low enough absorption losses.