Stern-Gerlach Probability: Find the Probability

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SUMMARY

The discussion focuses on calculating the probability of +z atoms passing through a series of Stern-Gerlach selectors, specifically a +x selector followed by a -z selector. The initial state of the atoms is represented as |\uparrow_z>, and after passing through the +x selector, 50% of the atoms are polarized in the +x direction. Subsequently, when these +x polarized atoms encounter the -z selector, 50% of them will pass through, resulting in a total probability of 25% for the atoms to successfully pass through both selectors.

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cscott
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Homework Statement



We're learning some basic quantum mechanics by studying the stern-gerlach experiment so some of my terminology might be a bit off as it might be particular to this book, I'm not sure.

Say we have +z atoms (magnetic moment in +z direction?) shot through a +x selector followed by a -z selector. I need to find the probability that the atoms pass through.

Should I get probabilities 1/2 * 0 = 0. So 0 percent make it out?

What happened to that latex guide on here btw? I don't know how to make bras or kets or up/down arrows.
 
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What's the initial state of the system ? Then what happens to it afterwards ?
 
The initial state would be |\uparrow_z>

Then there is an +x selection measurement so wouldn't 50% get filtered out?

Then the -z selector would block the 50% from the first measurement?
 
cscott said:
The initial state would be |\uparrow_z>

Then there is an +x selection measurement so wouldn't 50% get filtered out?
Then the -z selector would block the 50% from the first measurement?

No. After the x selector, the atoms are polarized in the x direction, but this means that half of those left will pass the z selector and be polarized in the z direction.
QM spin works like that.
 
So 50% of the +z atoms would get selected in the +x selection and be polarized in +x. Then another 50% of those +x atoms will get slected in the -z selector? Which means 25% would make it through in total?
 
Can anyone verify this reasoning?
 

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