Polarization-independent single-photon switch based on a fiber-optical Sagnac interferometer for quantum communication networks

TL;DR

This paper demonstrates a fiber-optical Sagnac interferometer-based single-photon switch with polarization independence, high extinction ratio, and compatibility with existing telecom systems, advancing quantum network routing capabilities.

Contribution

It introduces a polarization-independent single-photon switch using a fiber Sagnac interferometer with commercial components, suitable for quantum communication networks.

Findings

Achieved over 19 dB extinction ratio.

Implemented with off-the-shelf telecom components.

Demonstrated polarization-independent routing of single photons.

Abstract

An essential component of future quantum networks is an optical switch capable of dynamically routing single-photons. Here we implement such a switch, based on a fiber-optical Sagnac interferometer design. The routing is implemented with a pair of fast electro-optical telecom phase modulators placed inside the Sagnac loop, such that each modulator acts on an orthogonal polarization component of the single-photons, in order to yield polarization-independent capability that is crucial for several applications. We obtain an average extinction ratio of more than 19 dB between both outputs of the switch. Our experiment is built exclusively with commercial off-the-shelf components, thus allowing direct compatibility with current optical communication systems.