All-optical routing of single photons with multiple input and output ports by interferences

TL;DR

This paper presents a waveguide-cavity system that enables all-optical routing of single photons across multiple ports by controlling photon phases, without extra control fields, at the quantum level.

Contribution

It introduces a novel waveguide-cavity design for phase-controlled photon routing at the single-photon level without additional control fields.

Findings

Routing controlled by photon phases at low photon numbers

No need for external control fields

Achieves routing at the quantum (single-photon) level

Abstract

We propose a waveguide-cavity coupled system to achieve the routing of photons by the phases of other photons. Our router has four input ports and four output ports. The transport of the coherent-state photons injected through any input port can be controlled by the phases of the coherent-state photons injected through other input ports. This control can be achieved when the mean numbers of the routed and control photons are small enough and require no additional control fields. Therefore, the all-optical routing of photons can be achieved at the single-photon level.