Quantum entanglement links particles through time, according to this study that
ID: 1373391 • Letter: Q
Question
Quantum entanglement links particles through time, according to this study that received some publicity last year:
New Type Of Entanglement Allows 'Teleportation in Time,' Say Physicists at The Physics arXiv Blog - Technology Review
S.J. Olson, T.C. Ralph, Extraction of timelike entanglement from the quantum vacuum, arXiv:1101.2565
S.J. Olson, T.C. Ralph, Entanglement between the Future and the Past in the Quantum Vacuum, Phys. Rev. Lett. 106, 110404 (2011)
Timelike entanglement may be regarded as a non-classical resource in a manner analogous to the spacelike entanglement that is often studied in the Minkowski vacuum, since any quantum information theoretic protocol may utilize conversion of timelike entanglement to spacelike entanglement as a step in the protocol.
I have read all the reviews in the popular press, most of the "time-travel-discovered" type, but I am looking for more sober comments, i.e. material written by physicists who have studied the paper. What does this result really mean? I would appreciate pointers to reviews, comments etc.
Explanation / Answer
I would venture that the paper is less significant than it seems, since in a universe with special relativity, what looks like a successful experimental proof of spatial entanglement to one observer will always look like a mix of space and time entanglement to another one.
Well stated Giulio; nice clean fallacy capture, and mea culpa for creating the fallacy. I'll try again when I get a moment. SR should still have geometric implications even for this spacelike separation, but not the way I just said
I need a diagram for this, but here goes: An entangled event has two classical terminators that within a single light cone that radiates from the point of entanglement. Both origin-to-terminator paths must remain causally isolated from the rest of the universe. One short path and one long path gives time-like separation; same-length paths gives space-like separation. Neither case differs when defining the consistency relationship between the terminus points. However, to classical observers the cases are different, with time-like akin to capturing half a Stern-Gerlach population