- #1
Petar Mali
- 290
- 0
In coordinate representation in QM probality density is:
[tex]\rho(\vec{r})=\psi^*(\vec{r})\psi(\vec{r})[/tex]
in RSQ representation operator of density of particles is
[tex]\hat{n}(\vec{r})=\hat{\psi}^{\dagger}(\vec{r})\hat{\psi}(\vec{r})[/tex]
Is this some relation between this operator and density matrix?
Operator of number of particles is
[tex]\hat{N}=\int d^3\vec{r}\hat{\psi}^{\dagger}(\vec{r})\hat{\psi}(\vec{r})[/tex]
Why I can now use
[tex]\hat{\psi}^{\dagger}(\vec{r})=\sum_k\hat{a}_k^{\dagger}\varphi^*_k(\vec{r})\qquad \hat{\psi}(\vec{r})=\sum_k\hat{a}_k\varphi_k(\vec{r})[/tex] ?
where [tex]\{\varphi_k\}[/tex] is complete ortonormal set.
Thanks
[tex]\rho(\vec{r})=\psi^*(\vec{r})\psi(\vec{r})[/tex]
in RSQ representation operator of density of particles is
[tex]\hat{n}(\vec{r})=\hat{\psi}^{\dagger}(\vec{r})\hat{\psi}(\vec{r})[/tex]
Is this some relation between this operator and density matrix?
Operator of number of particles is
[tex]\hat{N}=\int d^3\vec{r}\hat{\psi}^{\dagger}(\vec{r})\hat{\psi}(\vec{r})[/tex]
Why I can now use
[tex]\hat{\psi}^{\dagger}(\vec{r})=\sum_k\hat{a}_k^{\dagger}\varphi^*_k(\vec{r})\qquad \hat{\psi}(\vec{r})=\sum_k\hat{a}_k\varphi_k(\vec{r})[/tex] ?
where [tex]\{\varphi_k\}[/tex] is complete ortonormal set.
Thanks