Abstract
We study the connection between the charging power of quantum batteries and the fluctuations of the extractable work. We prove that in order to have a nonzero rate of change of the extractable work, the state of the battery cannot be an eigenstate of a “free energy operator,” defined by , where is the Hamiltonian of the battery and is the inverse temperature of a reference thermal bath with respect to which the extractable work is calculated. We do so by proving that fluctuations in the free energy operator upper bound the charging power of a quantum battery. Our findings also suggest that quantum coherence in the battery enhances the charging process, which we illustrate on a toy model of a heat engine.
- Received 19 September 2019
- Accepted 8 July 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.040601
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