Transmission of photonic Bell states over a 2x32dB, 144km free-space link

We successfully transmitted both photons of various Bell states over a 144 km free-space link between the islands of Tenerife and La Palma. Creating and transmitting more than $6\times10^6$ highly entangled photon pairs/s over the $2\times32$ dB channel we received $0.07$ pairs/s at the receiver. We were able to distinguish between $\left|\psi^-\right\rangle$ and $\left|\psi^+\right\rangle$ states and verified the presence of entanglement by violating a CHSH Bell inequality to $S=2.61\pm0.11$, 5 standard deviations above the classical limit of 2. Using a small and compact photon source, we effectively emulate quantum communication in a loss regime comparable to a two-link satellite communication scenario. Furthermore, we convincingly demonstrate the feasibility of 2-photon quantum communication protocols like dense coding, teleportation or quantum cryptography without reference frame over long distance. Finally, with a flight time of 0.5 ms the transmitted Bell states are the longest lived photonic Bell states ever reported.