In this article, a scheme for charging quantum batteries using the chain-STIRAP technique is proposed. For this purpose, first, a five-level quantum battery is considered and four pulses are used to charge this battery. It has been shown that by properly adjusting the maximum intensity and the time delay between pulses, the conditions of the chain -STIRAP technique can be established and charged the five-level quantum battery properly, so that the maximum amount of ergotropy is achieved. In this scheme, small changes in the parameters of the pulses, including the time delay between the pulses and the maximum value of the pulses, do not have much effect on the final ergotropy of the system. It is also shown that the proposed method in this scheme can be extended to charge quantum batteries with more than five levels.
In this article, a scheme for charging quantum batteries using the chain-STIRAP technique is proposed. For this purpose, first, a five-level quantum battery is considered and four pulses are used to charge this battery. It has been shown that by properly adjusting the maximum intensity and the time delay between pulses, the conditions of the chain -STIRAP technique can be established and charged the five-level quantum battery properly, so that the maximum amount of ergotropy is achieved. In this scheme, small changes in the parameters of the pulses, including the time delay between the pulses and the maximum value of the pulses, do not have much effect on the final ergotropy of the system. It is also shown that the proposed method in this scheme can be extended to charge quantum batteries with more than five levels.
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.
We derive fast protocols for charging a three-qubit Ising spin-chain quantum battery, using amplitude and phase control of the global transverse field. For weak coupling between the qubits in the chain, where the initial ground state of the system is the spin-down state, we find that the optimal strategy is to fix the control amplitude at its maximum value while properly varying the phase with time. For the strong coupling case, where the initial ground state is the one-excitation Dicke state [Formula: see text], we apply two related charging protocols. In the first approach we use a pulse-sequence derived numerically in the recent work (Stojanović and Nauth in Phys Rev A 108:012608, 2023. https://doi.org/10.1103/PhysRevA.108.012608 ), composed of delta Bang pulses and intervals where the control is switched off. We call this method fast charging via subspace decomposition, since it involves identifying and manipulating effective two-level subsystems. Here we find analytically the characteristics of the pulses composing the sequence, which were calculated numerically in the above reference. In the second approach, we apply a similar pulse-sequence with delta Bang pulses and Off intervals, but with a carrier frequency which brings on resonance the initial [Formula: see text] state and the target spin-up state of maximum energy. We call this method charging via resonant excitation. We calculate numerically the characteristics of the pulses in the sequence and find a shorter charging time compared to the non-resonant method inspired by the above reference. We also use numerical optimal control to solve the problem of full charging the quantum battery but for finite values of the control amplitude and find that, for some relatively large values of this bound, the optimal solution has similar structure with the sequence incorporating delta Bang pulses but longer duration, as expected. Although this study focuses on a three-spin chain, the proposed methodology can be also extended to larger spin-chains. The lowest and highest energy eigenstates need to be identified first, serving as the initial and target states. Then, optimal control can be exploited to find the amplitude and phase modulation of a field resonant to this transition, which maximize the stored energy in the battery for a given duration.
Quantum batteries are energy storage or extraction devices in a quantum system. Here, we present a closed-loop quantum battery by utilizing a circularly coupled three-state quantum system, and investigate its charging dynamics. The charging performance is greatly improved due to the existence of the third field in the system to form a closed-contour interaction. Through appropriately selecting the third control field, the maximum average power can be increased, even far beyond the ideal maximum power value of non-closed-loop three-level quantum battery. We study the effect of the global driving-field phase on the charging process and find that both the maximum extractable work (“ergotropy”) and the charging power vary periodically under different control fields, with a period of . Possible experimental implementation in nitrogen-vacancy spin is discussed as well.
One of the most important devices emerging from quantum technology are quantum batteries. However, self-discharging, the process of charge wasting of quantum batteries due to decoherence phenomenon, limits their performance, measured by the concept of ergotropy and half-life time of the quantum battery. The effects of local field fluctuation, introduced by the disorder term in the Hamiltonian of the system, on the performance of the quantum batteries is investigated in this paper. The results reveal that the disorder term could compensate disruptive effects of the decoherence, i.e., self-discharging, and hence improve the performance of the quantum battery via "incoherent gain of ergotropy" procedure. Adjusting the strength of the disorder parameter to a proper value and choosing a suitable initial state of the quantum battery, the amount of free ergotropy, defined with respect to the free Hamiltonian, could exceed the amount of initial stored ergotropy. In addition harnessing the degree of the disorder parameter could help to enhance the half-life time of the quantum battery. This study opens perspective to further investigation of the performance of quantum batteries that explore disorder and many-body effects.
Although implementing shortcuts to adiabaticity (STA) in open quantum systems remains challenging due to the complex control schemes required for such systems, their powerful ability to rapidly steer the system toward target states and their widespread applicability in quantum technologies have motivated us to explore their potential in quantum energy storage. In this work, we employ STA techniques to charge an open quantum battery and demonstrate that the extractable work (Ergotropy) from such a battery can be significantly enhanced by several times compared to the case where the battery is charged using a time independent driving field. Our results pave the way for accelerating the dynamics of open quantum systems and suggest promising applications in the development of high-performance, stable quantum batteries.
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 tf. We demonstrate that for very short charging time (tf), where the evolution is highly non-adiabatic, the stored energy and ergotropy are very small. However, with increasing tf we show that there is an optimal charging time, tfopt, 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 tf 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 tfopt and the corresponding thermal state using one-norm distance.