# A tunable single photon quantum router

## TL;DR

This paper introduces a highly efficient, tunable single-photon quantum router using coupled resonator waveguides and three-level atoms, capable of near-perfect routing controlled by an external field, with broad bandwidth applications.

## Contribution

It presents a novel design for a single-photon router that achieves near 100% efficiency and tunability, advancing quantum photonic routing technology.

## Key findings

- Achieves near 100% routing efficiency
- Operates as a four-way single-photon switch
- Routing controlled by external electromagnetic field

## Abstract

We propose an efficient single-photon router comprising two resonator waveguide channels coupled by several sequential cavities with embedded three-level atoms. We show that the system can operate as a perfect four-way single-photon switch. We also demonstrate that an incident single-photon propagating in one of the waveguides can be routed into one or the other output channels; such routing can be controlled by the external classical electromagnetic field driving the atoms. We argue that, under appropriate conditions, the efficiency of such routing can be close to 100\% within a broad operational bandwidth, suggesting various applications in photonics.