In the recent Xinhua press release China launches first-ever quantum communication satellite the last two sentences (which are two paragraphs) outline several distinct experiments planned for the Quantum Experiments at Space Scale (QUESS) satellite in conjunction with either one or two ground stations.
With the help of the new satellite, scientists will be able to test quantum key distribution between the satellite and ground stations, and conduct secure quantum communications between Beijing and Xinjiang's Urumqi.
QUESS, as planned, will also beam entangled photons to two earth stations, 1,200 kilometers apart, in a move to test quantum entanglement over a greater distance, as well as test quantum teleportation between a ground station in Ali, Tibet, and itself.
If I try to make an outline, I get the following.
- QKD between the satellite and ground stations
- secure quantum communications between Beijing and... Urumqi
- beam entangled photons to two earth stations (1,200km apart)
- test quantum teleportation between a ground station... and itself
Here is my current understanding of those:
- QUESS produces a pair of entangled photons, sends one photon to a ground station and simultaneously measures the other internally.
- Don't understand - QKD by #3, or something different? Uses second public path for the encrypted data? Since Beijing to the Xinjiang Observatory is over 2400km, I'm thinking Store and Repeat?
- QUESS produces a pair of entangled photons, sends both photons - each to different ground stations for simultaneous measurement.
- Not sure - is this more of a "science experiment" related to entanglement but not necessarily for secure information transfer?
I'm looking for an answer which helps me understand the most likely interpretation of the experiments mentioned in items 2 and 4 - a clarification of what the experiment is likely to be intended to do, not an explanation of the underlying quantum mechanics of entanglement.
Because of the mixture of publicly conducted science and government interests, the answer may need to contain a bit of speculation or 'most likely experimental scenario' from someone familliar with the field.
This helpful answer and the Nature article cited there has helpful information, and also goes on to mention some confusion on geographic sites in a different (New York Times) article. But I don't find an answer to my question there.