Monday, January 21, 2008

Communication with Quantum Entanglement?

One of the most interesting phenomena in quantum mechanics, first proposed by Schrodinger along with Einstein, Podolsky, and Rosen way back in the 1930's is entanglement. This is a quantum phenomenon where two systems (two particles that have interacted say) become linked across space and time. When this happens the properties of the particles become correlated, so if you know the spin of one of the particles, you know the spin of it's entangled partner, or should I say you know what the result of a measurement on the spin of its partner would be-even if it was located on the other side of the universe.

Entanglement is often described with two parties denoted as Alice and Bob each taking one member of the entangled pair. Generally its a given that although this phenomenon is interesting, it would not be possible to communicate using it-because measurement results would appear to be random unless Alice and Bob compare their results. A paper released a few years ago indicates that under certain special circumstances, it may in fact be possible to transmit some information from Alice to Bob in a quantum way. I have provided a link to this interesting (but dense) paper below.

The paper makes use of two topics I cover in detail in Quantum Mechanics Demystified-spin and the density matrix ( I also cover these topics in detail in my book Quantum Computing Explained published by Wiley). In any case, if you understand quantum theory at the level of quantum mechanics demystified you will be able to grasp this paper.

1 comment:

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