Toward A Reconfigurable Quantum Network Enabled by a Broadband Entangled Source

TL;DR

This paper demonstrates a reconfigurable quantum network using a broadband entangled photon source and wavelength multiplexing, enabling multiple entangled pairs for quantum key distribution over fiber.

Contribution

It introduces a broadband, spectrally correlated entangled photon source compatible with standard telecom grids for reconfigurable quantum networking.

Findings

Generated over 25 frequency-conjugate entangled pairs within a 90 nm bandwidth.

Successfully distributed entangled pairs over 40 km fiber for QKD.

Achieved secure key rates up to 20 bits/sec per pair.

Abstract

We present a proof-of-principle experimental demonstration of a reconfigurable entanglement distribution scheme utilizing a poled fiber-based source of broadband polarization-entangled photon pairs and dense wavelength-division multiplexing. A large bandwidth (> 90 nm, centered at 1555 nm) and highly spectrally correlated nature of the entangled source can be exploited to allow for the generation of more than 25 frequency-conjugate entangled pairs when aligned to the standard 200 GHz ITU grid. In this work, three frequency-conjugate entangled pairs are used to demonstrate quantum key distribution, with the wavelength-selective switching done manually. The entangled pairs are delivered over 40 km of actual fiber, and an estimated secure key rate of up to 20 bits/s per bi-party is obtained.