It "doesn't involve radio waves, or any form of energy. The principle it works on, the constant of simultaneity, is analogous in some ways to gravity ... One point has to be fixed, on a planet of certain mass, but the other end is portable."

About Card's ansible, it says, "Card's description of the ansible's functions in Xenocide involves a fictional subatomic particle, the philote. In the "Enderverse", the two quarks inside a pi meson can be separated by an arbitrary distance while remaining connected by "philotic rays"."

So perhaps Card's "Xenocide" (1991) is where the entanglement => FTL communication myth began?

It's a great novel, by the way.