Talk:Quantum Experiments at Space Scale

Puzzling
This article doesn't appear to explain why spaceflight is necessary for quantum experiments. Kortoso (talk) 19:44, 19 August 2016 (UTC)
 * At the end of section "Secure Key Distribution" it gives the reason: you can optically "connect" two far away places on earth in a relatively undisturbed way because the photons "only" need to go twice through a few km of the (disturbing) atmosphere.82.51.63.118 (talk) 23:20, 20 August 2016 (UTC)

QKD with/without entanglement
In the article there seems to be some confusion with respect to QKD (quantum key distribution). The usual (and technically less challenging) type doesn't need entanglement, it suffices to send single photons with random polarization. Another way to make QKD is to produce pairs of entangled photons and send one of each to each party. The satellite does the latter (which ensures that the satellite itself can't possibly eavesdrop on the communication). In the article the two types of QKD are mixed up. 82.51.63.118 (talk) 23:08, 20 August 2016 (UTC)