We focus on quantum entanglement as the main route to quantum communications in order to exceed the powers of existing classical techniques.
In light of applications such as quantum cryptography and quantum teleportation, we understand the significance of the extension of quantum-entanglement-based protocols to global distances, not least because it has resulted in considerable practical interest.
We have been able to experimentally demonstrate entanglement-based quantum key distribution over 144 km. This is achieved by measuring a photon locally at the Canary Island of La Palma while a second is sent over an optical free-space link to Tenerife, where the Optical Ground Station of the European Space Agency acts as the receiver.
This exceeds previous free-space experiments by more than an order of magnitude in distance, and is an essential step towards future satellite-based quantum communication and experimental tests of the limits of quantum physics.
For further information on research of this kind at the University of Bristol, please visit the Centre for Quantum Photonics website.