Researchers supported in part by the QuantERA II(opens in new window) and Qurope(opens in new window) projects have successfully teleported information from one light-emitting device to another thanks to a phenomenon called quantum entanglement. To do this, the scientists converted light to wavelengths that work with regular internet cables, suggesting that teleportation could eventually work with the fibre optic infrastructure in use today.
A genuine quantum process
The use of quantum entanglement means that information was sent between the two devices by teleporting the quantum state of light, not by transmitting an ordinary signal through the fibre. As described in their study(opens in new window) published in the journal ‘Nature Communications’, the researchers achieved a 72.1 % success rate in their efforts. The fact that this significantly exceeds the 66.7 % classical fidelity threshold in quantum information transfer proves that genuine quantum transportation occurred as opposed to classical transmission. The fidelity measurement shows how closely the teleported quantum state matches the original state. For the purposes of their experiment, the scientists converted light to a common telecommunication wavelength of 1 515 nanometres, which perfectly suits the fibre optic cables currently used for internet connections. At this wavelength, the quantum state of the particles of light – photons – remains unaltered, meaning that the light does not lose much strength at all over great distances. Frequency converters were used to change the photons from their natural colour to a wavelength compatible with fibre optic technology.
Not one, but two light-emitting devices
According to an article(opens in new window) posted on ‘StudyFinds’, what made this experiment stand out was the use of two independent light sources, unlike earlier studies that used a single light-emitting device. The researchers used two tiny semiconductor nanocrystals called quantum dots to generate the individual photons. Each quantum dot operated independently, in its own ultra-cold chamber. The first quantum dot emitted a single photon carrying the information that was to be teleported. The second quantum dot emitted pairs of entangled photons that provided the quantum connection needed for teleportation to take place. “Ensuring these two independent devices could work together required solving a tricky problem: each naturally produced light at a slightly different wavelength,” explains the ‘StudyFinds’ article. This problem was fixed by the frequency converters that made the photons similar enough for quantum teleportation to happen. Before this technology can be widely used, a number of obstacles first need to be overcome, such as the extremely cold temperatures (267 °C) required for the experiment, and the complex and costly wavelength conversion system. Nevertheless, the research results, achieved with the support of the QuantERA II (QuantERA II ERA-NET Cofund in Quantum Technologies) and Qurope (Quantum Repeaters using On-demand Photonic Entanglement) projects, mark an important development for semiconductor-based quantum light sources. For more information, please see: QuantERA II project website(opens in new window) Qurope project website(opens in new window)