A prototype quantum hard drive capable of storing information for up to six hours paves way for a future worldwide ultra-secure data encryption network based on quantum information.
Developed by researchers at the Australian National University (ANU), the device described in the latest issue of Nature stores data for more than 100 times longer than previous systems.
“We believe it will soon be possible to distribute quantum information between any two points on the globe,” said Manjin Zhong, from ANU's Research School of Physics and Engineering (RSPE), the lead author of the study.
“Quantum states are very fragile and normally collapse in milliseconds. Our long storage times have the potential to revolutionise the transmission of quantum information.”
The ANU scientists, in cooperation with a team from the University of Otago, stored quantum information in atoms of a solid europium crystal by directly writing the quantum state onto the nuclear spin of the material using laser light.
To make sure the data is stored securely, the team subjected the crystal to magnetic fields to see whether the delicate quantum information remains unchanged.
The researchers believe the innovative technique provides a viable alternative to the existing method of transmitting quantum data via lasers through optical fibres.
“Our storage times are now so long that it means people need to rethink what is the best way to distribute quantum data. Even transporting our crystals at pedestrian speeds we have less loss than laser systems for a given distance,” Zhong said.
“We can now imagine storing entangled light in separate crystals and then transporting them to different parts of the network thousands of kilometres apart. So, we are thinking of our crystals as portable optical hard drives for quantum entanglement.”
For comparison – the current laser-based optical-fibre quantum data networks are capable of covering distances up to 100km.
Quantum information promises unbreakable encryption because quantum particles such as photons of light can be created in a way that intrinsically links them. Interactions with either of these entangled particles affect the other, no matter how far they are separated, which makes it virtually impossible for anauthorised individuals to interfere in the process.