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Is there a possibility (if not real than at least theoretical) that we could measure the spin of an electron continously over some (even very short) period of time, so that it does not change during the measurement?

I'm thinking maybe of something like observing it continuously... Is it achievable?

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    $\begingroup$ Er, something like this? en.wikipedia.org/wiki/Quantum_Zeno_effect $\endgroup$
    – zeldredge
    Commented Oct 12, 2015 at 18:46
  • $\begingroup$ You can measure quantum systems continuously (or piece by piece), acquiring only a small amount of information about the state during each time interval. Correspondingly, you will only disturb the state little during each time step. However, the total disturbance will be determined by the total information gain, so there is nothing you will win as compared to an instant measurement. $\endgroup$
    – Norbert Schuch
    Commented Oct 13, 2015 at 15:21

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You can do a quantum zero type measurement if the spin of that particle has a well defined single particle spin state and you zeno it to stay in that state.

But this would require that it not have its spin entangled with any other particle (in order to have the well defined single particle spin state).

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  • $\begingroup$ The Zeno effect allows to freeze a spin in a known state, so it is not a continuous measurement which allows to acquire information about the initial state of the system. $\endgroup$
    – Norbert Schuch
    Commented Oct 13, 2015 at 15:22

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