Quantum batteries are quantum devices that exploit superposition, non-classical correlations, and entanglement to enhance energy charging and discharging. First proposed in 2013 [1], they have since inspired a wide range of theoretical models, yet experimental realizations remain limited, making accurate simulations essential for guiding device architectures and material choices. Here, we study exciton discharge dynamics in a symmetry-protected excitonic quantum battery [2,3], where an exciton is stored in a dark state that is shielded from loss channels by symmetry, and controlled symmetry breaking provides a tunable discharge mechanism (Figure 1).

To realistically capture the dynamics of such devices, we employ an open quantum systems framework, in which noise and dissipation from the environment are encoded via a spectral density. The environment is modeled as a collection of harmonic oscillators, and the spectral density specifies the frequency-dependent system-bath coupling, enabling energy relaxation, decoherence, and non-Markovian memory effects to be included without explicitly resolving all environmental degrees of freedom. We systematically investigate how the form of the spectral density influences the discharge dynamics, comparing Debye-Drude and Ohmic-like environments characterized by the Ohmicity exponent (\(s=\)0.5, 1.0, 1.5, and 3.0 correspond to sub-Ohmic, Ohmic, moderately super-Ohmic, and strongly super-Ohmic baths, respectively). We further examine the effects of the system-bath coupling strength and bath cutoff frequency. Across all parameter regimes studied, the Debye-Drude spectral density yields the largest exciton population transfer to the discharge site. For the Ohmic-like environments, the relative performance depends on both coupling strength and cutoff frequency. Increasing the coupling strength generally enhances population transfer for the Ohmic and moderately super-Ohmic baths, while the strongly super-Ohmic bath remains the least effective. In contrast, the sub-Ohmic bath exhibits a non-monotonic response, showing reduced transfer at stronger coupling. Variations in the cutoff frequency produce a different ordering of bath performance, indicating that the characteristic frequency distribution of the environment plays a distinct role from the overall coupling strength in determining discharge efficiency. These results clarify how environmental structure governs exciton transfer in a symmetry-protected quantum battery and help inform the design of physically realistic environments in experimentally realizable devices.

(1) Alicki, R.; Fannes, M. Physical Review E 2013, 87, 042123.
(2) Liu, J.; Segal, D.; Hanna, G. The Journal of Physical Chemistry C 2019, 123, 18303–18314.
(3) Khodadad, Z.; Hanna, G. The Journal of Chemical Physics 2026, 164, 064305.