Tuesday, June 10, 2008

Entanglement and Quantum Mechanics

A discussion over at http://www.badastronomy.com/bablog/covers the concept of entangled quantum states. The effect is that if one photon of a pair of matched photons has a particular state (+ in our case), then the other half of the matched pair would also be a +. Now if they are separated by a great distance and the first one changes it's state to a - (minus sign) the other also changes to a - sign instantaneously. In other words they seem to communicate their state in spite of being separated at such long distances as to be invisible to each other. We're talking about astronomical distances out to the very edge of the universe. So then the idea comes up that because they know their state, and change together while being separated, they could be used to send coherent information. Now, because there is probability concerns involved, only the sender and receiver of the message would know by prearrangement how to read the message. See, you start out by sending the + and - states of the photons in a digital string. But to someone intercepting the message, they'd have to know what basic coding string was being used to decode the message. At this point the explanation of coded messaging goes off into another whole area of encryption theory and really doesn't have anything to do with the entanglement concept except that entanglement could be used to send encrypted messages. A message "in the clear" could also be sent without having to use any tricky encryption.

One idea that comes to mind for entangled messaging is to use it in computers. If you build a computer with entangled photons or any entangled pair of subatomic parts and change one of the pair, you change the other one. This would cut down on the time it takes to compute. One of the things slowing computers down is the physical length electrons have to travel to send computed + and - (1 or 0) in a digital string. Designers try to get around this by packing more and more CPU elements together in smaller pieces. There is a limit on manufactures' abilities to make things smaller. And we seem to be at about the limit with present ingredients and manufacturing techniques. So developing entangled states would speed things up and allow a tighter packing of computing circuits.

I have to stop now because things are not making much sense to me and I know it ain't making any sense to you either. So, I leave it at that.

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