A Quantum Memory Storage Prototype

eldavojohn writes "An Australian National University project has completed a proof-of-concept storage unit that relies on bringing light to a standstill inside a crystal and then releasing it later for a read-once storage device. There are a few complexities to work out, such as the -270 degrees Celsius requirement to stop the light. And there is an interesting side effect noted by the team lead: 'We could entangle the quantum state of two memories, that is, two crystals. 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.' Hopefully this will lead to a better understanding and simple testing of quantum entanglement."

Comments

Re:FTL communications

[TexVex]

Because you cannot both entangle the two photons and store information in them at the same time. Entangled quantum particles are by definition in a "superposition of states", which basically means that their values are essentially random when observed.

Storing information in a quantum particle requires observing it, to wrangle it into a desired non-random state. Observation destroys entanglement, because an observed particle is no longer in a superposition of states. Entangling quantum particles requires re-superposing their states. Creation of entanglement destroys information.

So, a pair of these quantum memory cells can store only one of the three following:
1> The same information
2> Unrelated information
3> Entanglement (which is unknown randomness that is correlated between the two cells)

The "spooky-action-at-a-distance" thing is in how the observations of separated but entangled quantum systems correlate. It's weirder than it seems on the surface -- read up on what a Bell Inequality is. That's where the strangeness is; because separate observation of entangled pairs of particles correlates more than is possible by the rules of classical physics and the rules of math and logic.