It may soon be possible to extract information from a quantum object - and even manipulate it - without simultaneously destroying its delicate quantum state. The result would be a boon for quantum computing, which requires control over such states. It would also defy a thought experiment dreamed up by physicist Erwin Schrödinger: in principle it is now possible to peek inside his box without endangering the life of the precarious pussycat inside.
States that are mutually exclusive in classical physics can exist simultaneously in the weird world of quantum mechanics - a situation called a superposition. To illustrate this effect, Schrödinger imagined putting a cat in a box along with a device that would release poison to kill it, depending on the random decay of a radioactive atom. Because the atom's quantum state only takes a definite value when someone looks at it, the cat is both dead and alive until the box is opened.
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