Photon State Teleported 25 km

Swiss physicists have attained quantum teleportation over more than four times the distance they achieved a decade ago.

A team at the University of Geneva has successfully teleported the quantum state of a photon to a crystal via 25 km of optical fiber. The researchers had previously achieved teleportation over 6 km; those results were published in 2003 in Nature (doi: 10.1038/nature01376).

Crystals contain photonic information after the teleportation. Courtesy of GAP/University of Geneva.

Teleportation “requires the efficient distribution of entanglement between remote nodes of a network,” the researchers noted in the current study. Here polarization-entanglement was established between a single photon in a rare earth/ion-doped crystal and a flying telecommunications-wavelength photon.

In the study, one of two entangled photons was propelled along the 25-km optical fiber, while the other was sent to the crystal. The researchers found that the quantum state of a single photon can be maintained while transporting it into the crystal, and without the two coming directly into contact.

The experiment demonstrated “quantum teleportation of the polarization state of a telecom-wavelength photon onto the state of a solid-state quantum memory,” the researchers wrote in the study.

The study was published in Nature Photonics (doi: 10.1038/nphoton.2014.215).

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