A versatile source of polarisation entangled photons for quantum network applications

TL;DR

This paper presents a versatile, guided-wave method for generating high-quality polarization-entangled photons with tunable bandwidths, suitable for various quantum network applications like quantum key distribution and quantum memories.

Contribution

A novel fully guided-wave approach using a high-brilliance waveguide and advanced transcriber to produce and manipulate polarization entanglement across a wide spectral range.

Findings

Achieved high entanglement fidelities at bandwidths of 25 MHz, 540 MHz, and 100 GHz.

Demonstrated the ability to generate any pure polarization entangled state.

Showcased the scheme's suitability for diverse quantum network applications.

Abstract

We report a versatile and practical approach for generating high-quality polarization entanglement in a fully guided-wave fashion. Our setup relies on a high-brilliance type-0 waveguide generator producing paired photon at a telecom wavelength associated with an advanced energy-time to polarisation transcriber. The latter is capable of creating any pure polarization entangled state, and allows manipulating single photon bandwidths that can be chosen at will over five orders of magnitude, ranging from tens of MHz to several THz. We achieve excellent entanglement fidelities for particular spectral bandwidths, i.e. 25 MHz, 540 MHz and 100 GHz, proving the relevance of our approach. Our scheme stands as an ideal candidate for a wide range of network applications, ranging from dense division multiplexing quantum key distribution to heralded optical quantum memories and repeaters.