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QI: Fachverband Quanteninformation

QI 11: Quantum Thermodynamics

QI 11.7: Vortrag

Dienstag, 19. März 2024, 11:15–11:30, HFT-TA 441

Storing work in thermal equilibrium: ergotropy of mean-force Gibbs states — •Karen Hovhannisyan¹ and Janet Anders^{1, 2} — ¹University of Potsdam, Institute of Physics and Astronomy, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany — ²Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

Subsystems of a strongly-interacting many-body system are not in Gibbs states when the system is in thermal equilibrium as a whole. Such non-Gibbsian states can store work in the form of ergotropy. We use this observation to devise a quantum battery that is simply a detachable subsystem of a many-body lattice. The charging cycle consists of connecting the subsystem, letting it equilibrate, and then disconnecting and extracting work from it. This cycle requires very little external control and the charged state of the battery, being a part of global thermal equilibrium, can be maintained indefinitely and for free. As out system we use 1D and 2D harmonic lattices with strong long-range interactions. We show that the stored work, quantified by the Gaussian ergotropy, can increase polynomially with the size of the subsystem, showing that this setup can be potentially useful in practical implementations of noise-robust quantum batteries.

Keywords: Quantum battery; Mean-force Gibbs state; Ergotropy; Second law of thermodynamics; Long-range systems