I studied quantum information/foundations to research level, so may be able to give some input and obviate some of the wilder interpretations. This paper isn't

I studied quantum information/foundations to research level, so may be able to give some input and obviate some of the wilder interpretations. This paper isn't directly in my field of interest (don't know much about relativity), so I'm happy to be corrected if I say something stupid. You've probably heard that quantum information processing uses the "qubit" as an information primitive. A qubit is not itself a particle, but a "degree of freedom" which can be in one of a range of states. This degree of freedom could be spin, polarization, energy, and so on and so on. Unlike bits, a pair of qubits can be entangled, which means that their joint state is not decomposable into a statistical mixture of independent pairs of states. The paper considers two degrees of freedom associated with photons emitted from the accretion disks of spinning black holes: polarization and orbital angular momentum (OAM). Essentially, there are two qubits per photon. After some reasonable assumptions and calculations we find that the two qubits are highly entangled; in fact, as entangled as it's possible for two qubits to be. The author speculates that may be able to detect this by measuring such photons with modern equipment. I suppose the motivation is that we might be able to use them for actual information processing tasks (although as far as I can see there's no benefit to this over preparing entangled qubits ourselves). That's about it, I think. No time-travel, no communication, but a small point of interest.