Number operator help

pleasehelpmeno

I am sorry I don't know what you mean, is it like [itex] N/V = \int (\frac{1}{(2\pi)^3}) d^3 k d^3 k' a^\{dagger} a = \int (\frac{1}{(a2\pi)^3}) d^3 k a^\{dagger} a [/itex]

pleasehelpmeno

so as in the Volume cancels with the second d^3 k' term?

andrien

N=Ʃ_k a⁺a=V/(2∏)³∫d³k a⁺a,V is volume.