I Odds of getting pairs -- QM version

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The discussion focuses on calculating the odds of observing pairs of electrons with the same energy level in a quantum system of 16 energy levels, each containing electron pairs with opposite spins. The calculations suggest that the probabilities for observing two pairs, one pair, and no pairs are approximately 0.033, 0.464, and 0.503, respectively. The user questions whether the differences in probabilities between classical and quantum scenarios are significant and if their calculations are valid. The thread emphasizes the importance of understanding these differences in quantum mechanics. Overall, the inquiry seeks clarity on the implications of quantum behavior in such measurements.
anuttarasammyak
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As a spin out of How to calculate these odds?
https://www.physicsforums.com/threads/how-to-calculate-these-odds.1012014/
I have a question for quantum objects.
Question : An atom system has 16 different energy levels filled with 16 electron pairs of opposite spin direction. We pick up or measuring energy of 4 of them. Calculate odds for numbers of pairs of same energy we get in the observation results.

I assume:
If we observe spin z component of electrons together, the result is same as the thread.
If we do not observe it the number of cases are
2 pairs : ##\ _{16}C_2 = 120##
1 pair : ##\ _{16}C_1 \ _{15}C_2 = 1680 ##
0 pair : ##\ _{16}C_4 = 1820##
Total case number is ##120+1680+1820=3620##
So the probabilities are
P(2)=0.033 > 0.003 which is the result in the thread
P(1)=0.464 > 0.187
P(0)=0.503 < 0.810

I would like to know whether such a difference between classical and quantum cases takes place or not and if yes also this calculation is reasonable or not.
 
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