Ergotropy, Rényi Mutual Information, and Steered Coherence in Quantum Batteries

ABSTRACT We investigate ergotropy, defined as the maximum work extractable through unitary operations, along with Rényi mutual information and steered coherence within the context of quantum batteries. Beginning with the thermal Gibbs state of a two‐qubit system, we systematically analyze the dependence of these quantities on various parameters, including coupling strength , anisotropy parameter , external magnetic field , and temperature . Our results reveal that the extrema of ergotropy, Rényi mutual information, and steered coherence do not coincide, suggesting that distinct types of correlations contribute differently to the extractable work. Nevertheless, these quantities exhibit common critical thresholds. The non‐analytic characteristics observed stem from eigenvalue crossings in the Hamiltonian spectrum, while an increase in temperature serves to suppress all quantities due to thermal decoherence.