News of the WeekQuantum Physics

In Clone Wars, Quantum Computers Need Not Apply

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Science  09 May 2003:
Vol. 300, Issue 5621, pp. 884
DOI: 10.1126/science.300.5621.884

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If bloodthirsty legions of identical self-replicating robots bent on the destruction of humanity haunt your dreams, rest easy. Science has proven that they can't exist--at least not if they have quantum brains. In a paper submitted to Physical Review Letters, two physicists have shown that it is impossible to build a quantum "universal constructor"--a quantum computer that has the ability to spawn perfect copies of itself.