Quantum battery with non-Hermitian charging

Abstract

We propose a design of a quantum battery exploiting the non-Hermitian Hamiltonian as a charger. In particular, starting with the ground or the thermal state of the interacting (noninteracting) Hamiltonian as the battery, the charging of the battery is performed via parity-time ($\mathcal{PT}$)- and rotational-time ($\mathcal{RT}$)-symmetric Hamiltonians to store energy. We report that such a quenching with a non-Hermitian Hamiltonian leads to an enhanced power output compared to a battery with a Hermitian charger. We identify the region in the parameter space which provides the gain in performance. We also demonstrate that the improvements persist with the increase of system size for batteries with both $\mathcal{PT}$- and $\mathcal{RT}$-symmetric chargers. In the $\mathcal{PT}$-symmetric case, although the anisotropy of the $\mathrm{XY}$ model does not help in the performance, we show that the $\mathrm{XXZ}$ model as a battery with a non-Hermitian charger performs better than that of the $\mathrm{XX}$ model having certain interaction strengths. We also exhibit that the advantage of non-Hermiticity remains valid even at finite temperatures in the initial states.