Quantum harvester enabling energy transfer without entropy transfer

We consider a foundational question in energy harvesting: Given a partly random energy source, is it possible to extract the energy without also transferring randomness or accepting another thermodynamical cost We answer this in the positive, describing scenarios and protocols where in principle energy is extracted from a field with randomness but without any randomness being transferred and without energy dissipation. We explain why these protocols do not violate basic physical principles. Such protocols fundamentally outperform existing methods of rectification which dissipate power or demonlike feedback protocols which transfer randomness to the feedback system. The protocols exploit the possibility of the harvesting system taking several trajectories that lead to the same final state at a given time. A key example involves Rabi oscillations between energy levels, exploiting the multitude of rotation axes in the state space. The quantum system is deterministically excited to the highest energy level after interacting with the source for a fixed amount of time, irrespective of the random initial phase of the external potential. These realizations show the value of Rabi-oscillation-type techniques for enhancing energy harvesting. © 2025 American Physical Society.