Why is $\langle \hat{A} \rangle = tr(\hat{\rho} \hat{A})$?
87962
Why is $\langle \textbf R \rangle =Tr \rho R$ here $\rho$ is the state density matrix
34147
$\|u\|\leq \|u+av\| \Longrightarrow \langle u,v\rangle=0$
20503
Meaning of inner product $\langle \vec{r} | \psi(t)\rangle $
79647
Where does the term $|\psi\rangle\langle\psi|$ come from while calculating the expectation value?
103061
Why is it true that $\mathrm{adj}(A)A = \det(A) \cdot I$?
8554
Proof: $\mathrm{adj}(\mathrm{adj}(A)) = (\mathrm{det}(A))^{n-2} \cdot A$ for $A \in \mathbb{R}^{n\times n}$
39080
What is the spectrum of $\hat x \hat p + \hat p \hat x$?
44843
What is the difference between $|0\rangle $ and $0$?
129170
Deriving the expectation of $[\hat X,\hat H]$
150199
How to prove for a finite group that $|\langle g \rangle|=o(g)$?
11557
How to prove $\det(e^A) = e^{\operatorname{tr}(A)}$?
147564
Why does $(A/I)\otimes_R (B/J)\cong(A\otimes_R B)/(I\otimes_R 1+1\otimes_R J)$?
153684
In quantum mechanics, is $|\psi\rangle$ equal to $\psi(x)$?
13682
Is $\langle a,b \mid a^2b^2=1 \rangle$ a semidirect product of $\mathbb{Z}^2$ and $\mathbb{Z}_2$?
151621
$G$ a group and $H, K\mathrel{\unlhd}G$. Assuming that $H \cap K = \{1_G\}$ and $G = \langle H, K \rangle$, prove that $G \cong H \times K$
30996
If $\langle Ta, a\rangle \in \mathbb{R}$ for all $a$ then $T$ is self-adjoint
128985
Show that $\langle x,y\rangle_A = \langle Ax,Ay\rangle$ is an inner product on $\mathbb R^n$