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.
The physics.gen-ph category on arXiv is a little odd, a little uncomfortable, and hard to describe. Here are a couple of quotes from discusions of arXiv moderation commenting on it:
"There is one middle option between acceptance and rejection: Dubious papers can be shunted to a category called “general physics,” or “gen-ph.” At best, gen-ph is a home for papers that don’t fit neatly into any other category; at worst, it is a crackpot dumping ground. Either way, it allows moderators to dodge the drama that comes with out-and-out rejections. For many authors, though, being relegated to gen-ph is just as galling as being rejected outright: As one such researcher told Reyes-Galindo, having his paper reclassified to gen-ph felt like a deliberate attempt to diminish the paper’s impact." -- http://oren365.tech/news/What-Counts-as-Science? (via Google cache)
"Personally, I have never had a problem with the arXiv moderation. I had a paper reclassified from gen-ph to gr-qc once by a well-meaning moderator, which is how I learned that gen-ph is the dump for borderline crackpottery. (How would I have known? I don’t read gen-ph. I was just assuming someone reads it.)" -- http://backreaction.blogspot.com/2016/05/the-holy-grail-of-c...
EDIT: I don't mean this as direct criticism of this paper, which might potentially be fantastic and just fit better in the general category for one reason or another than in gr-qc. (Or, some moderator might have been too harsh: entirely possible!) But I wanted to share some of the unspoken background information that many physicists would think about when seeing this link.
Ovidiu, being a researcher, can you please tell what your scientific CV is, especially related to the topics of the paper?
I see you've submitted different papers to arxiv:
Have you had any interactions and/or reactions from the other researchers in the fields? Have you published somewhere else?
Perhaps they are talking to each other.. .
Edit -- You and I really are quite alike in thought sometimes. You must come and visit Southampton sometime now the house is a bit more sorted.
No, really! :)
This was ragingly interesting, but outside papers like these I wondered what the application of this at this stage might be; Great sci-fi could be had, was my conclusion.
I wonder what it means.