From maximum work to maximum power in an optimally controlled quantum Ising Otto engine
Abstract
In finite-time quantum Otto engines, maximizing power requires balancing the duration of the unitary strokes against the losses from nonadiabatic excitations. We address this trade-off in an Otto engine with a free-fermion working medium, using quantum optimal control. Having determined the single-particle energy scales that maximize ideal work at fixed reservoir temperatures, we realize them as the two endpoint Hamiltonians of a transverse-field Ising chain, connected by a path that crosses the quantum critical point. Optimal control of the unitary strokes yields near-ideal work on a time scale growing linearly with system size, instead of quadratically as for linear driving. We derive a time-rescaling relation that maps protocols with different energy scales onto a single reference problem and, for complete thermalization strokes of fixed duration, use it to build an analytical model of the cycle power. The model predicts two competing maximum-power regimes: a slow branch that approaches the ideal work, and a fast, size-independent branch that trades work for a shorter cycle and dominates above a crossover size, in quantitative agreement with numerical optimal-control results. It also identifies power-optimal energy scales that differ from the work-optimal ones and further increase the power. Our results provide a predictive approach to jointly optimizing the operating conditions and finite-time dynamics of quantum heat engines.
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BibTeX
@misc{arezzo2026from,
title = {{From maximum work to maximum power in an optimally controlled quantum Ising Otto engine}},
author = {Vincenzo Roberto Arezzo and Davide Rossini and Giuseppe E. Santoro and Giulia Piccitto},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08025},
eprint = {2611.08025},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08025},
}
RIS
TY - UNPB
TI - From maximum work to maximum power in an optimally controlled quantum Ising Otto engine
AU - Vincenzo Roberto Arezzo
AU - Davide Rossini
AU - Giuseppe E. Santoro
AU - Giulia Piccitto
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08025
UR - https://arxiv.org/abs/2611.08025
AB - In finite-time quantum Otto engines, maximizing power requires balancing the duration of the unitary strokes against the losses from nonadiabatic excitations. We address this trade-off in an Otto engine with a free-fermion working medium, using quantum optimal control. Having determined the single-particle energy scales that maximize ideal work at fixed reservoir temperatures, we realize them as the two endpoint Hamiltonians of a transverse-field Ising chain, connected by a path that crosses the quantum critical point. Optimal control of the unitary strokes yields near-ideal work on a time scale growing linearly with system size, instead of quadratically as for linear driving. We derive a time-rescaling relation that maps protocols with different energy scales onto a single reference problem and, for complete thermalization strokes of fixed duration, use it to build an analytical model of the cycle power. The model predicts two competing maximum-power regimes: a slow branch that approaches the ideal work, and a fast, size-independent branch that trades work for a shorter cycle and dominates above a crossover size, in quantitative agreement with numerical optimal-control results. It also identifies power-optimal energy scales that differ from the work-optimal ones and further increase the power. Our results provide a predictive approach to jointly optimizing the operating conditions and finite-time dynamics of quantum heat engines.
ER -