Fast stable adiabatic charging of open quantum batteries.

Abstract

Recent theoretical and experimental protocols for the stable and effective charging of open quantum batteries (QBs), in particular adiabatic charging of three-level QBs via stimulated Raman adiabatic passages, have sparked renewed interest in adiabatic quantum dynamics. A central question is whether exploiting the adiabatic master equation could provide advantages over the previous studies in the effective charging of open QBs. To answer this question, we revisit the adiabatic charging of three-level QB by 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. It is also worth emphasizing that our protocol to investigate the charging process of QBs based on the adiabatic master equation despite the previous studies is not phenomenological and is general. We analyze the dependence of the stored energy, ergotropy, as well as the efficiency of the QB on the total time of evolution t_{f}. We demonstrate that for very short charging time (t_{f}), where the evolution is highly nonadiabatic, the stored energy and ergotropy are very small. However, by increasing t_{f} we show that there is an optimal charging time t_{f}^{opt} in which, at low temperatures, we could fully charge the battery and effectively extract the entire amount of energy from it. Note that the optimal charging time could be decreased by adjusting the strength of the coupling between the system and environment and also be the appropriate choice of the Hamiltonian parameters, which, in turn, speed up the charging process. However, we show that for very long charging time t_{f} the charging energy, ergotropy, and efficiency decrease due to thermal excitations. Furthermore, to obtain more insights about the problem we investigate the distance between the density matrix of a system at optimal charging time t_{f}^{opt} and the corresponding thermal state by using the one-norm distance.