Adiabatic charging of open quantum battery

Abstract

We revisit the adiabatic charging of a three-level QBs, using the adiabatic quantum master equation formalism. We restrict ourselves to the weak-coupling regime with an Ohmic thermal bath and investigate the effects of relaxation and dephasing on the charging process. We analyze the dependence of the stored energy, ergotropy as well as efficiency of QB on the total time of evolution $t_f$. We demonstrate that for very short charging time ($t_f$), where the evolution is highly non-adiabatic, the stored energy and ergotropy are very small. However, with increasing $t_f$ we show that there is an optimal charging time, $t_f^{opt}$, for maximum energy charging such that at low temperatures we could fully charge the battery and effectively extract the whole amount of energy from it. Note that, the optimal charging time could be decreased by adjusting strength of the coupling between system and environment and also appropriate choice of the Hamiltonian parameters which in turn speed up the charging process. On the other hand, we show that for very long charing time $t_f$ the charging energy, ergotropy and efficiency decrease due to thermal excitations. Furthermore to get more insights about the problem we investigate the distance between density matrix of system at optimal charging time $t_f^{opt}$ and the corresponding thermal state using one-norm distance.