A research team in China have trapped light in a piece of crystal for an hour, a breakthrough in information technology that could have important applications such as transporting sensitive data in hack-proof form . The crystal could be kept in a device about the size of a suitcase, and transported. If someone opened the device without a key, the light – and the sensitive information it carried – would be destroyed. The technology would offer unprecedented security with the potential to “extend the communication distance to global scale”, said Professor Li Chuanfeng of the University of Science and Technology of China, in Hefei. Li was lead author of the paper, published in journal Nature Communications on Sunday. Light is a particle of energy without mass, and it travels faster than anything in Einstein’s universe. For decades, physicists around the world have tried all kinds of ways to slow it down. Showering extremely cold atoms on a beam of light, for instance, could slow it to 60km/h (37mph). But even at the most gentle pace, the elusive light particles were still extremely difficult to capture and store. The previous best attempt, by a German team eight years ago, kept them alive for only about a minute. Li’s team used a unique crystal doped with rare earth elements including europium and yttrium to trap the light particles, or photons. The crystal was unique because when the light hit, it could absorb the photons without losing any of their physical traits, such as spin and polarisation. The atoms of the crystal had a natural vibration of their own that could kill the light. To reduce the disturbance, Li and colleagues cooled the tiny crystal ball to almost absolute zero temperature. Zhang Huaijin, a professor of material science at Shandong University, who was not involved in the study, said the experiment added yet more proof of China’s leading position in crystal technology. To store the light, the crystal’s physical properties must be thoroughly understood, and the crystal should be extremely pure and grown precisely with a secret formula of earth elements, according to Zhang. Despite its novelty, the crystal used in the Hefei experiment could be manufactured in bulk by China’s crystal suppliers, paving way for the mass application of the light storage technology, he said. China is a dominant supplier of high-quality crystals that have been used in a wide range of cutting-edge scientific instruments, including the International Space Station and most of the world’s largest particle colliders. But just like other forms of energy, light decays quickly. To keep it on for as long as possible, the researchers fired two different beams of laser into the crystal. The laser beams were carefully tuned, so that they could keep the original light on without changing the photons’ physical properties. China’s rare earth dominance casts shadow over Europe’s climate targets After an hour’s storage, the light’s physical properties remained 96 per cent the same as the original, good enough for most practical applications. The Hefei team said further upgrades and tweaks to the hardware could increase the duration of light storage. A previous study by a team from Australia suggested that, in theory, light could stay in crystal for up to six hours, but the previous record before the Hefei experiment was about a minute, achieved in 2013 by a team of physicists from Germany. Using this method, sensitive information could be carried in public without fear of being stolen or hacked, according to the researchers. China is building the world’s largest quantum communication network using optical fibres and satellites. The technology uses the fundamental law of subatomic physics to protect the transmission of encrypted information. But optic fibres could not reach everywhere, and many places do not have the powerful telescopes required to pick up the faint laser signals from a quantum satellite. In such circumstances, light-storage crystals could be more suitable to use, according to Li. The technology could also find applications in astronomy. The light captured by many telescopes, for instance, could be stored in crystal balls and later analysed together in one place. This would massively improve the final resolution of the images captured, according to the researchers.