It seems to me that this would allow nearly instantaneous communication anywhere in the solar system.
It takes a radio signal anywhere from 4 minutes to 24 minutes to travel from Mars to Earth, depending on the relative positions of the two planets at any given time in their orbits.
And Mars is the closest planet to Earth.
but first you have to transport one there
It’s well established that when two electrons are entangled, no matter how far away they are moved, they “communicate” instantaneously. Change the spin of one, and the spin of the other instantly changes.
I believe each particle is at two places at the same time, or, alternatively, has a double. Do something to its double kight years away and it will be immediately affected.
Only if you can control the states on one end, which is apparently not possible.