Experimental demonstration of a BDCZ quantum repeater node

Understand

Quantum communication is a method that offers efficient and secure ways for the exchange of information in a network.

• Large-scale quantum communication (of the order of 100 km) has been achieved; however, serious problems occur beyond this distance scale, mainly due to inevitable photon loss in the transmission channel.
• Quantum communication eventually fails when the probability of a dark count in the photon detectors becomes comparable to the probability that a photon is correctly detected.
• To overcome this problem, Briegel, D\"{u}r, Cirac and Zoller (BDCZ) introduced the concept of quantum repeaters, combining entanglement swapping and quantum memory to efficiently extend the achievable distances.