- #1
Petar Mali
- 290
- 0
All number of bosons in case of Bose condensation is
[tex]N=N_0+\sum_{\vec{p}\neq 0}N_{\vec{p}}[/tex]
I found in one book that [tex]N_0=\hat{b}^+_0\hat{b}_0[/tex]
In that book author say that [tex]\hat{b}^+_0\hat{b}_0=N_0[/tex] and [tex]\hat{b}_0\hat{b}^+_0=N_0+1\approx N_0[/tex]
so
[tex][\hat{b}_0,\hat{b}^+_0]\approx 0[/tex]
and from there
[tex]\hat{b}_0=\hat{b}^+_0=\sqrt{N_0}[/tex]
Is this true? Little seems ridiculous to me because I do not know how he could get
[tex]\hat{b}_0\hat{b}^+_0=N_0+1\approx N_0[/tex]
without using
[tex][\hat{b}_0,\hat{b}^+_0]=1[/tex]
So
[tex]1\approx 0[/tex]
:)
Am I
right?
I have problem also with calling for example [tex]N_{\vec{p}}=\hat{b}^+_{\vec{p}}\hat{b}_{\vec{p}}[/tex] because [tex]N_{\vec{p}}[/tex] is eigen -value of this operator!
[tex]N=N_0+\sum_{\vec{p}\neq 0}N_{\vec{p}}[/tex]
I found in one book that [tex]N_0=\hat{b}^+_0\hat{b}_0[/tex]
In that book author say that [tex]\hat{b}^+_0\hat{b}_0=N_0[/tex] and [tex]\hat{b}_0\hat{b}^+_0=N_0+1\approx N_0[/tex]
so
[tex][\hat{b}_0,\hat{b}^+_0]\approx 0[/tex]
and from there
[tex]\hat{b}_0=\hat{b}^+_0=\sqrt{N_0}[/tex]
Is this true? Little seems ridiculous to me because I do not know how he could get
[tex]\hat{b}_0\hat{b}^+_0=N_0+1\approx N_0[/tex]
without using
[tex][\hat{b}_0,\hat{b}^+_0]=1[/tex]
So
[tex]1\approx 0[/tex]
:)
Am I
right?
I have problem also with calling for example [tex]N_{\vec{p}}=\hat{b}^+_{\vec{p}}\hat{b}_{\vec{p}}[/tex] because [tex]N_{\vec{p}}[/tex] is eigen -value of this operator!