Team develops read-once holograms using quantum light memory

An Australian team says it’s developed the most efficient quantum memory for light ever, and has used it to create read-once holograms.

The Australian National University researchers used a new technique to stop and control light from a laser, manipulating electrons in a crystal cooled to -270 degrees Celcius.

“Light entering the crystal is slowed all the way to a stop, where it remains until we let it go againWhen we do let it go, we get out essentially everything that went in as a three-dimensional hologram, accurate right down to the last photon,” says lead researcher Morgan Hedges.

“Because of the inherent uncertainty in quantum mechanics, some of the information in this light will be lost the moment it is measured, making it a read-once hologram. Quantum mechanics guarantees this information can only be read once, making it perfect for secure communication.”


The new memory could also be a leading prospect for quantum computing, as well as allowing tests of fundamental physics, such as how quantum entanglement interacts with of the theory of relativity.

“We could entangle the quantum state of two memories, that is, two crystals,” says team leader Dr Matthew Sellars.

“According to quantum mechanics, reading out one memory will instantly alter what is stored in the other, no matter how large the distance between them. According to relativity, the way time passes for one memory is affected by how it moves. With a good quantum memory, an experiment to measure how these fundamental effects interact could be as simple as putting one crystal in the back of my car and going for a drive.”

Dr Sellars’ team previously managed to ‘stop’ light in a crystal for over a second, more than 1,000 times longer than had been possible. He says the team is now bringing together systems to combine high efficiency with storage times of hours.