- #1
rbwang1225
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The model of damped harmonic oscillator is given by the composite system with the hamiltonians ##H_S\equiv\hbar \omega_0 a^\dagger a##, ##H_R\equiv\sum_j\hbar\omega_jr_j^\dagger r_j##, and ##H_{SR}\equiv\sum_j\hbar(\kappa_j^*ar_j^\dagger+\kappa_ja^\dagger r_j)=\hbar(a\Gamma^\dagger+a^\dagger\Gamma)##.
Now, the initial reservior density is ##R_0=\prod_je^{-\hbar\omega_jr_j^\dagger r_j/k_BT}(1-e^{-\hbar\omega_j/k_BT})##
We have the operators in the interaction picture,
##\tilde\Gamma_1(t)=\tilde\Gamma^\dagger(t)=\sum_j\kappa_j^*r_j^\dagger e^{i\omega_jt}## and ##\tilde\Gamma_2(t)=\tilde\Gamma(t)=\sum_j\kappa_jr_j e^{-i\omega_jt}##
I want to calculate ##<\tilde\Gamma_j(t)>_R=Tr_R(R_0\tilde\Gamma_j(t))## which is identical to zero.
I have no idea why ##<\tilde\Gamma_j(t)>_R##'s are zero.
Now, the initial reservior density is ##R_0=\prod_je^{-\hbar\omega_jr_j^\dagger r_j/k_BT}(1-e^{-\hbar\omega_j/k_BT})##
We have the operators in the interaction picture,
##\tilde\Gamma_1(t)=\tilde\Gamma^\dagger(t)=\sum_j\kappa_j^*r_j^\dagger e^{i\omega_jt}## and ##\tilde\Gamma_2(t)=\tilde\Gamma(t)=\sum_j\kappa_jr_j e^{-i\omega_jt}##
I want to calculate ##<\tilde\Gamma_j(t)>_R=Tr_R(R_0\tilde\Gamma_j(t))## which is identical to zero.
I have no idea why ##<\tilde\Gamma_j(t)>_R##'s are zero.