Efficient charging and discharging of a superconducting quantum battery through frequency-modulated driving

The quantum battery (QB), which can potentially store or dispatch energy more efficiently with quantum advantage, has attracted considerable attention lately in the field of quantum thermodynamics. With its quantum advantage, a QB could be charged more efficiently than the classical battery. In this paper, we theoretically and experimentally exploit the frequency-modulated stimulated Raman adiabatic passage (fmod-STIRAP) technique to improve the charging (discharging) efficiency of a cascaded three-level QB that is constituted by a superconducting transmon qutrit. The evolution of the qutrit and its thermodynamic properties are analyzed by carrying out the three-level quantum state tomography on the device. Our experimental results, which are confirmed by numerical simulations, show that the fmod-STIRAP technique yields remarkable advantages in population, ergotropy, and power in the charging (discharging) process.