PH would be parallel to n

The question doesn’t posit that.

Spoiler alert: the image has no relation to the question, it’s just something OP picked to elicit that “3D geometry” feeling. There is a point A’, a point B, point C, and point D, but no point P or H or n.

quantum computing is revolutionary because it allows instant transmission of information across unlimited space

False and common misconception! In quantum mechanics there is even a theorem called the no-communication theorem that mathematically proves that no information can ever be transmitted by quantum entanglement. Sorry!

Gravity—the curvature of space-time—can’t stop changes in the curvature of spacetime from propagating outward.

This is false. If it were true, you could build a device to communicate from inside a black hole event horizon. By waving around a heavy ball you would create gravitational waves that a sensitive enough LIGO outside the black hole could detect. But this is impossible. You would create gravitational waves, yes, but they would fall towards the center singularity same as you, and will never penetrate and escape the event horizon.

The yyyy-mm-dd format (ISO 8601) is the only one that is unambiguous, because no one so far in history has ever used the yyyy-dd-mm format (at least until some xkcd-reading jokester probably will start using it just out of spite). I use ISO 8601 everywhere. It has the additional benefit that filenames get sorted correctly in lexographical order.