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Can this measurement be done?

  1. Dec 10, 2011 #1
    Just trying to follow Giancarlo Ghirardi reasoning in his book about differentiating between pure and mixture esembles.

    Is it possible to perform a measurement on an observable that, if it were in a superposition, a certain value would return?
  2. jcsd
  3. Dec 10, 2011 #2
    Yes. There is the hoary double-slit experiment. If you insist on a single measurement, the recent experiment on entanglement that involved two diamonds qualifies.
  4. Dec 10, 2011 #3
    Ah ok.

    Because X would return if the state was in |A+1>+|A-1>, and Y would return if the state was in |A+1>-|A-1>.

    After measurement of the observable, would either X or Y return, plus a definite A+1 or A-1? I guess when the measurement is done, its checking to see if its in a superposition, but once measurement is over, you'd expect the superposition to have collapsed.
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