Scientists at the National Institute of Standards and Technology (NIST) have conducted an experiment confirming that quantum communication over long distances is possible. Research team has successfully "teleported" quantum information carried in light particles over 100 km (62 miles) of optical fiber, breaking a previous record by four times.
The term quantum teleportation involves the transfer, or remote reconstruction, of information encoded in quantum states of matter or light. Teleportation has the potential of offering new possibilities such as unbreakable encryption and advanced code-breaking techniques.
The basic method for quantum teleportation was first proposed over 20 years ago. Different research groups have been successful in teleporting quantum information over even longer distances, however, these experiments have been conducted in free space, while the ability to perform teleportation over conventional optical fiber is far more flexible solution for network designs.
In this experiment, scientists have managed to transfer quantum information contained in one photon to another photon. The information has been transmitted over 102 km of spooled fiber in a NIST laboratory in Colorado. This record breaking achievement has been made possible by advanced single-photon detectors designed and constructed at NIST.
“Only about 1 percent of photons make it all the way through 100 km of fiber. We never could have done this experiment without these new detectors, which can measure this incredibly weak signal,” NIST’s Marty Stevens said.
The exciting research results were published in the Optical Society Journal on September 23, 2015.
The graphic describing how the researchers conducted teleportation of quantum information over optical fibre. Image credit: K.Irvine/NIST
This discovery is unique in its way, as so far, a large amount of quantum data has been lost in fiber and transmission rates and distances achieved have been quite low. The new technique could be used to construct devices that would be able to resend data cyclically in order to extend network reach, which could open possibilities for building a "quantum internet".
Up until now, it was considered the quantum repeaters will have to rely on atoms or other matter, which has posed a difficult engineering challenge and would also significantly slow down transmission.
The experiment has used quantum states indicative of when a single photon arrives in a sequence of time slots. Four of NIST's photon detectors have been positioned in a way to enable filtering out particular quantum states. These detectors have been constructed to rely on superconducting nanowires made of molybdenum silicide. They are capable of recording over 80% of arriving photons and to reveal if they are in the same or different time slots each just 1 nanosecond long.
These experiments have been performed at wavelengths commonly used in telecommunications.
Teleportation could be successfully conducted in only 25% of the transmissions, so far, as the experiment filtered out and focused on a limited combination of quantum states. Because of the highly efficient detectors, researchers have been successful in teleporting the desired quantum state in 83% of the maximum possible successful transmissions, on average. All experimental runs with different starting properties exceeded the mathematically significant 66.7% threshold for proving the quantum nature of the teleportation process.
Video credit: Phil Magnini
- "Quantum teleportation over 100 km of fiber using highly efficient superconducting nanowire single-photon detectors" - Hiroki Takesue, Shellee D. Dyer, Martin J. Stevens, Varun Verma, Richard P. Mirin, Sae Woo Nam - The Optical Society Journal (2015) - doi:10.1364/OPTICA.2.000832
Featured image: Quantum teleportation artist's impression. Image credit: Phil Magnini
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