Optimal work extraction from finite-time closed quantum dynamics

Date

Aug 19, 2025

Time

3:00 PM - 4:00 PM

Speaker

Ryusuke Hamazaki

Affiliation

RIKEN

Language

en

Main Topic

Physik

Other Topics

Physik

Description

Recent advancements in quantum technologies have motivated extensive studies on how thermodynamic quantities can be controlled using quantum operations. In particular, extracting work from a quantum battery via controlled unitary operations is one of the central issues in non-equilibrium quantum thermodynamics. While the maximal extractable work without any control constraint is known as ergotropy, it remains highly nontrivial to determine how much work can be obtained in a finite-time operation when the control Hamiltonians are constrained. Here, we present two general results concerning such finite-time optimal work extraction under the assumption that the magnitude of the control Hamiltonian is bounded. The first theorem establishes a trade-off relation between work and power, two crucial performance metrics for quantum batteries. This implies that a rapid protocol is necessary to achieve high power, thereby justifying the importance of our finite-time framework. The second theorem applies under the additional assumption that the set of control operations forms a Lie algebra. In this case, the theorem states that the optimal protocol is remarkably simple: one can use a time-independent Hamiltonian determined by a closed nonlinear equation. We verify our theorems in concrete setups involving both few-level and many-body systems.

Last modified: Aug 19, 2025, 7:38:47 AM