Where is this setup shown? I cannot find it on the internet. The spin is returned to the original polarization rather than spin-up or down which would be expected from the intermediate superposition from the initial Stern Gerlach device followed by a second device which gives back the original polarization of the electron. Superposition of an electron's random polarization can be recovered from sending the electron through two Stern Gerlach devices which create a spin-up and spin-down superposition which when run through the next device returns the electron to the random spin polarization.
closed as unclear what you're asking by Emilio Pisanty, John Rennie, Kyle Kanos, Jon Custer, glS Jan 12 '18 at 9:39
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