Thursday, September 29, 2005

No-cloning theorem limits

The no-cloning theorem is misleading. I mean, yes you cannot clone arbitrary quantum states perfectly, but you can clone arbitrary quantum states approximately with good enough overlap fidelity among the clones. This opens the door to presponse signal nonlocality. Gaussian continuous variable states in particular can be effectively cloned. It may mean an error in the Susskind-Hawking ideas about information recovery from evaporating black holes that depends upon naive use of the no-cloning theorem.

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