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arXiv · 2608.12055

Enhancing the power of a quantum heat engine via control of the system--reservoir coupling

Sabrina Burgardt·Julian Feß·Silvia Hiebel·Eric Lutz·Artur Widera
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Abstract

The non-equilibrium properties of open quantum systems are determined by the microscopic laws governing energy exchange with their environment. In particular, an enhancement of the performance of quantum heat engines has been predicted by speeding up the dynamics through control of the system--bath interaction. However, direct microscopic control of heat transfer between the machine and the reservoir has remained elusive so far. Here, we experimentally demonstrate such control in a quantum Otto engine realized with ultracold Cs-133 atoms coupled to an atomic reservoir of ultracold Rb-87 atoms. Heat exchange between the two is mediated by inelastic s-wave collisions whose energy-dependent scattering cross sections lead to an asymmetric equilibration dynamics in the isochoric heating and cooling strokes. By tuning the kinetic temperature of the atomic reservoir, we modify the associated microscopic scattering rates, and thereby the heat transfer law, giving control over the time allocation within the engine cycle through control over the microscopic, multi-exponential relaxation dynamics. This enables power output optimization at fixed efficiency. Our results establish microscopic control of system-reservoir interactions as a tool for manipulating heat flow at the nanoscale and engineering the finite-time performance of quantum thermal machines.

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Sabrina Burgardt, Julian Feß, Silvia Hiebel, Eric Lutz, Artur Widera. 2026-08-12. Enhancing the power of a quantum heat engine via control of the system--reservoir coupling. https://arxiv.org/abs/2608.12055

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