A research team seems to have broken the most recent record of distance for quantum teleportation, posted by a Chinese research group. This new record is about the distance between New York City and Philadelphia and concerns the quantum state of a single photon. While it also might sound that the transfer happens instantaneously, the steps required to read out the teleported quantum state ensure that it doesn’t travel faster than the speed of light, which would break causality.
Quantum teleportation uses the phenomenon of quantum entanglement, which links quantum particles. Although this link is fragile and invisible, two entangled photons have correlated opposite polarization states. Quantum mechanics states that each photon’s polarization remains undecided until one of them is measured. At that time, the polarization snaps into place, even if many kilometers separate the entangled pair.
It allows a detour to the physics theorem of no-cloning. That theorem states that a quantum object cannot be perfectly copied. This teleportation doesn’t create a copy, it simply shifts the quantum information from one place to another, destroying the original in the process.
This can mean that information can be sent in this fashion and this information could be the gateway to more secure forms of communications between stations. A new European and Canadian research group claims to have transported quantum information from one of the Canary Islands to another, which are 143 kilometers apart. The paper is currently on arXiv.org, but comes from a reputable research group. It will no doubt be published after it’s been peer-reviewed.
Reference: “Quantum teleportation over 143 kilometres using active feed-forward” by Xiao-Song Ma, Thomas Herbst, Thomas Scheidl, Daqing Wang, Sebastian Kropatschek, William Naylor, Bernhard Wittmann, Alexandra Mech, Johannes Kofler, Elena Anisimova, Vadim Makarov, Thomas Jennewein, Rupert Ursin and Anton Zeilinger, 5 September 2012, Nature.