Quantum State Transfer over 1200 km Assisted by Prior Distributed Entanglement

Long-distance quantum state transfer (QST), which can be achieved with the help of quantum teleportation, is a core element of important quantum protocols. A typical situation for QST based on teleportation is one in which two remote communication partners (Alice and Bob) are far from the entanglement source (Charlie). Because of the atmospheric turbulence, it is challenging to implement the Bell-state measurement after photons propagate in atmospheric channels. In previous long-distance freespace experiments, Alice and Charlie always perform local Bell-state measurement before the entanglement distribution process is completed. Here, by developing a highly stable interferometer to project the photon into a hybrid path-polarization dimension and utilizing the satellite-borne entangled photon source, we demonstrate proof-of-principle QST at the distance of over 1200 km assisted by prior quantum entanglement shared between two distant ground stations with the satellite Micius. The average fidelity of transferred six distinct quantum states is 0.82 1 0.01, exceeding the classical limit of 2/3 on a single copy of a qubit.

Automated summary

Long-distance quantum state transfer is a core element of important quantum protocols, but implementing Bell-state measurement after photon propagation in atmospheric channels is challenging due to atmospheric turbulence. By developing a stable interferometer and utilizing a satellite-borne entangled photon source, proof-of-principle QST was demonstrated at a distance of over 1200 km with an average fidelity of 0.82±0.01.