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.