Wednesday, March 30, 2016

operators - Quantum non-unitary transformation?



Let us say that I apply a non-unitary transformation $\def\ket#1{| #1\rangle} \def\braket#1#2{\langle #1|#2\rangle} \hat A$ to the ket's: $$\ket{\psi} \rightarrow \hat A \ket{\psi}$$ $$\ket{\phi}\rightarrow \hat A \ket{\phi}$$ Clearly in this case the probability: $$P=|\braket{\phi}{\psi}|^2$$ Will change. What physically is going on here? i.e. why for unitary operators we can perform such a transformation but for non-unitary operators we can't?




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classical mechanics - Moment of a force about a given axis (Torque) - Scalar or vectorial?

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