Related Experiment Video
Updated: Jun 21, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Efficient entanglement distribution over 200 kilometers
J F Dynes1, H Takesue, Z L Yuan
1Toshiba Research Europe Limited, Cambridge Research Laboratory, Cambridge CB4 0GZ, UK. james.dynes@crl.toshiba.co.uk
Abstract:
Here we report the first demonstration of entanglement distribution over a record distance of 200 km which is of sufficient fidelity to realize secure communication. In contrast to previous entanglement distribution schemes, we use detection elements based on practical avalanche photodiodes (APDs) operating in a self-differencing mode. These APDs are low-cost, compact and easy to operate requiring only electrical cooling to achieve high single photon detection efficiency. The self-differencing APDs in combination with a reliable parametric down-conversion source demonstrate that entanglement distribution over ultra-long distances has become both possible and practical. Consequently the outlook is extremely promising for real world entanglement-based communication between distantly separated parties.
Related Concept Videos
Distribution of Molecular Speeds
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
Energy Associated With a Charge Distribution
Distribution and Dispersion
Energy Stored In A Coaxial Cable
In the simplest form, a coaxial cable can be represented by two long hollow concentric cylinders in which the current flows in opposite directions. The magnetic field inside and outside the coaxial cable is determined by using Ampère's law. The magnetic field inside...
Extraction: Partition and Distribution Coefficients
For extracting a solute from an aqueous phase into an organic...
