SAMOP 2023 – wissenschaftliches Programm

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QI: Fachverband Quanteninformation

QI 29: Quantum Thermodynamics and Open Quantum Systems II

QI 29.2: Vortrag

Donnerstag, 9. März 2023, 14:45–15:00, B302

Correlations facilitate ergotropy transmission — •Rick Simon, Janet Anders, and Karen Hovhannisyan — University of Potsdam, Institut für Physik und Astronomie, 14476 Potsdam, Germany

Ergotropy quantifies the amount of unitarily extractable work stored in a system, and it is routinely used to measure the ``charge level'' of quantum batteries. A fundamental primitive in any (future) quantum power grid will be transmitting ergotropy from one system to another. Here we study energy-preserving unitary transmission channels for the case where both systems are qubits. More specifically, we take two noninteracting qubits and apply a joint unitary that commutes with the total Hamiltonian. When the initial state is factorized, we find that part of the transmitted ergotropy will necessarily be lost. However, the transmission can be lossless when the initial state is correlated. Moreover, despite the fact that no energy is injected into the total system during the transmission, the receiver may gain more ergotropy than is lost by the emitter. This extra gain is achieved at the expense of the correlations between the systems, which affects the reusability of the transmission channel. The degradability problem of the transmission-facilitating correlations is mitigated by the fact that these correlations need not be finely tuned. Indeed, by analyzing large sets of randomly sampled initial states, we found that, for a fixed (high enough) value of mutual information, most initial states incur no losses during ergotropy transmission.