Physicists have set a new distance record after successfully transporting quantum data over 100 kilometers of optical fiber. This is four times farther than the previous record.
The work by researchers at the National Institute of Standards and Technology (NIST)confirms that quantum communication is feasible over long distances in fiber. Other research groups have teleported quantum information over longer distances in free space, but the ability to do so over conventional fiber-optic lines offers more flexibility for network design.
The new record involved the transfer of quantum information contained in one photon—its specific time slot in a sequence— to another photon transmitted over 102 km of spooled fiber in a NIST laboratory in Colorado.
Not to be confused with Star Trek’s fictional “beaming up” of people, quantum teleportation involves the transfer, or remote reconstruction, of information encoded in quantum states of matter or light.
Teleportation is useful in both quantum communications and quantum computing, which offer prospects for novel capabilities such as unbreakable encryption and advanced code-breaking, respectively. The basic method for quantum teleportation was first proposed more than 20 years ago and has been performed by a number of research groups, including one at NIST using atoms in 2004.
“Only about 1 percent of photons make it all the way through 100 km of fiber,” NIST’s Marty Stevens says. “We never could have done this experiment without these new detectors, which can measure this incredibly weak signal.”
The achievement was made possible by advanced single-photon detectors designed and made at NIST.
Because the experiment filtered out and focused on a limited combination of quantum states, teleportation could be successful in only 25 percent of the transmissions at best. Thanks to the efficient detectors, researchers successfully teleported the desired quantum state in 83 percent of the maximum possible successful transmissions, on average.
Top Illustration: Gabriel Andrés Trujillo Escobedo