STAznanost

Discovery by Slovenian researchers has potential for advancing quantum communication systems

Ljubljana, 14 June - Scientists from Slovenia's Jožef Stefan Institute (JSI) and the German Max Planck Institute have made a breakthrough in the field of quantum light in liquid crystals, such as the ones in TV screens. This will allow for the development of more effective quantum communication systems, the researchers said.

Until now, the quantum light or entangled photons were only created in solid crystals where manipulating and monitoring the quantum properties of light was made more difficult by the rigid crystal structure.

JSI researchers Aljaž Kavčič, Matjaž Humar and Nerea Sebastian and their colleagues from the Max Planck Institute were able to design the quantum light in organic matter for the first time, in liquid crystals. They published their findings in the Nature scientific journal.

According to Humar, the main advantages of entangled photons in liquid crystals are more flexibility and more utility. "Our research showed for the first time that the properties of quantum light in liquid crystals, which have the properties of an intermediary state of matter between liquid and solid, can be changed with a simple electric signal," Humar told the STA.

"We can imagine this by imagining a lightbulb changing colour. If we wanted for the lightbulb to give off red light one time and green light the next time, we had to change the lightbulb. Now we can change the colour by pressing a button," he said.

This allows scientists to better control and adjust the quantum light in liquid crystals, which makes it easier to use in different applications. Similar to how brightness and colour of individual pixels can be changed on LCD screens, now the quantum properties of photons in liquid crystals can be changed.

Entangled particles are a special phenomenon in quantum mechanics, said Human, adding that quantum photons are among the most commonly used sources of such particles. "In this case there is a pair of photons that are interconnected, regardless of the distance between them, so we have to treat them as a whole," said Humar, adding that changing the state of one photon affects the other, even if they are far apart.

This interconnectedness has shown to be potentially useful for many different practical applications in quantum telecommunications, computing and metrology. "Our discovery speeds up the development of these technologies. This opens new possibilities for the development of more advanced, effective and safe quantum communication systems and more powerful quantum computers able of solving complex problems faster than classic computers," Humar said.

Quantum communications are an especially prospective field, he said, adding that JSI is working together with different institutes on research that could lead to the creation of quantum communication networks, first at a local and then at an international level. Such networks could connect European cities and significantly improve the security of data transfer, said Humar.