Swapped state | |Ψ^{−}〉_{03} | |Ψ^{+}〉_{03} |

V_{H/V} | 0.618 ± 0.067 | 0.610 ± 0.062 |

V_{P/M} | 0.607 ± 0.060 | 0.556 ± 0.065 |

V_{R/L} | 0.624 ± 0.056 | 0.542 ± 0.065 |

0.616 ± 0.035 | 0.569 ± 0.037 | |

W = 1/2 − (1 + 3 | −0.212 ± 0.027 | −0.177 ± 0.028 |

Local S value | 2.487 ± 0.287 | 2.469 ± 0.287 |

Numerical values of the measurement results including the individual visibilities V

_{H/M}, V_{P/M}, and V_{R/L}in the three mutually unbiased bases horizontal/vertical (H/V), plus/minus (P/M), and right/left (R/L) as well as the mean visibility V, the expectation value of the entanglement-witness operator W, and the locally measured S value. Over the 143-km free-space link the entanglement witness was more than 6 SDs beyond the classical bound of 0. This proved the presence of entanglement between photons “0” and “3” in the states ∣Ψ^{−}〉_{03}and ∣Ψ^{+}〉_{03}. The violation of a CHSH-type Bell inequality was shown locally on La Palma, underlining the quality of our setup. All outcomes are given for the swapped states ∣Ψ^{−}〉_{03}and ∣Ψ^{+}〉_{03}with the respective SDs assuming Poissonian photon statistics.