Routing single photons with quantum emitters coupled to nanostructures

TL;DR

This review discusses how quantum emitters coupled with nanostructures can be used to develop high-speed, efficient single-photon switches for quantum networks, combining theory and experiments across various platforms.

Contribution

It synthesizes theoretical proposals, experimental demonstrations, and key input-output methods for single-photon routing with quantum emitters in nanostructures.

Findings

Multiple physical platforms demonstrated single-photon switching.

Emphasizes importance of reporting speed, efficiency, and fidelity metrics.

Bridges quantum optics theory with experimental implementations.

Abstract

Quantum emitters coupled to nanophotonic structures are an excellent platform for controllable single-photon scattering. The tunable light-matter interaction enables the construction of a single-photon switch -- a device that can route a single photon from an input port to a selected output port. Such single-photon switching devices can be integrated into reconfigurable photonic circuits to actively control the photon propagation direction in a quantum network. Ideally, a single-photon switch should operate with high speed, efficiency, and fidelity, preserving the state of the input photon in the routing process. This review brings together key input-output methods from quantum optics, theoretical proposals of emitter-based single-photon routing mechanisms, and experimental demonstrations of single-photon switching devices across different physical platforms, including semiconductor quantum dots, neutral atoms, superconducting qubits, and color centers. We highlight the need for reporting the key figures of merit (speed/efficiency/fidelity) in future single-photon switch demonstrations to support further developments in the field.