Tez
Graduate Poster
- Joined
- Nov 29, 2001
- Messages
- 1,104
As a quick response to DD (sorry if someone mentioned this)
It is actually possible to prove, using the laws of quantum mechanics, that a quantum state cannot be "copied". That is, within the laws of quantum mechanics it is impossible to construct a machine into which I input a person in quantum state P, along with a lump of "substrate" (stuff the copy is to be made of) and out comes P P (two seperate copies of P).
THis is called the "no cloning theorem", where is probably should be called the "no duplication theorem".
Now, it is possible if you've measured the quantum state of the person in minute detail, to then reconstruct the state you've measured. Unfortunately the measurement in quantum mechanics is problematic - it doesnt reveal the "actual" state of the person, with various probabilities it reveals different outcomes. And after many such random outcomes on every atom of your body it is simple to show that the revealed state will be VERY far from that of a valid human being.
So at best we can do something like this: Meaure your quantum state exactly, turning you from person P into lump of sludge P'. Create two copies of P'.
Incidentally this is why in quantum teleportation the original quantum state is necessarily destroyed before it can be reconstructed at the receiving station...
Gotta race, no time to edit, hope this makes some sense...
Tez
It is actually possible to prove, using the laws of quantum mechanics, that a quantum state cannot be "copied". That is, within the laws of quantum mechanics it is impossible to construct a machine into which I input a person in quantum state P, along with a lump of "substrate" (stuff the copy is to be made of) and out comes P P (two seperate copies of P).
THis is called the "no cloning theorem", where is probably should be called the "no duplication theorem".
Now, it is possible if you've measured the quantum state of the person in minute detail, to then reconstruct the state you've measured. Unfortunately the measurement in quantum mechanics is problematic - it doesnt reveal the "actual" state of the person, with various probabilities it reveals different outcomes. And after many such random outcomes on every atom of your body it is simple to show that the revealed state will be VERY far from that of a valid human being.
So at best we can do something like this: Meaure your quantum state exactly, turning you from person P into lump of sludge P'. Create two copies of P'.
Incidentally this is why in quantum teleportation the original quantum state is necessarily destroyed before it can be reconstructed at the receiving station...
Gotta race, no time to edit, hope this makes some sense...
Tez