- #1
DuckAmuck
- 236
- 40
- TL;DR Summary
- Something about this is not clear.
The general uncertainty principle is derived to be:
[tex]\sigma_A^2 \sigma_B^2 \geq \left(\frac{1}{2} \langle \{A,B\} \rangle -\langle A \rangle \langle B \rangle \right)^2 + \left(\frac{1}{2i} \langle [A,B] \rangle \right)^2 [/tex]
Then it is often "simplified" to be:
[tex]\sigma_A^2 \sigma_B^2 \geq \left(\frac{1}{2i} \langle [A,B] \rangle \right)^2 [/tex]
But this simplification only works if:
[tex] \left(\frac{1}{2} \langle \{A,B\} \rangle -\langle A \rangle \langle B \rangle \right)^2 \geq 0 [/tex]
However is this condition always met? *
[tex]\sigma_A^2 \sigma_B^2 \geq \left(\frac{1}{2} \langle \{A,B\} \rangle -\langle A \rangle \langle B \rangle \right)^2 + \left(\frac{1}{2i} \langle [A,B] \rangle \right)^2 [/tex]
Then it is often "simplified" to be:
[tex]\sigma_A^2 \sigma_B^2 \geq \left(\frac{1}{2i} \langle [A,B] \rangle \right)^2 [/tex]
But this simplification only works if:
[tex] \left(\frac{1}{2} \langle \{A,B\} \rangle -\langle A \rangle \langle B \rangle \right)^2 \geq 0 [/tex]
However is this condition always met? *
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