Related Experiment Video
Updated: Jun 11, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Decoy-state quantum key distribution with polarized photons over 200 km
Yang Liu1, Teng-Yun Chen, Jian Wang
1Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Abstract:
We report an implementation of decoy-state quantum key distribution (QKD) over 200 km optical fiber cable through photon polarization encoding. This is achieved by constructing the whole QKD system operating at 320 MHz repetition rate, and developing high-speed transmitter and receiver modules. A novel and economic way of synchronization method is designed and incorporated into the system, which allows to work at a low frequency of 40kHz and removes the use of highly precise clock. A final key rate of 15 Hz is distributed within the experimental time of 3089 seconds, by using super-conducting single photon detectors. This is longest decoy-state QKD yet demonstrated up to date. It helps to make a significant step towards practical secure communication in long-distance scope.
Related Concept Videos
Potential Due to a Polarized Object
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
Group Polarization
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...
Electromagnetic Waves in Matter
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...
Propagation Speed of Electromagnetic Waves
