We demonstrate a microwave power-to-electrical energy conversion in a resonator-coupled double quantum dot. The system, operated as a photodiode, converts individual microwave photons to electrons tunneling through the double dot, resulting in an electrical current flowing against the applied voltage bias at input powers down to 1 fW. The device attains a maximum power harvesting efficiency of 2%, with the photon-to-electron conversion efficiency reaching 12% in the single-photon absorption regime. We find that the power conversion depends on thermal effects showing that thermodynamics plays a crucial role in the single-photon energy conversion.

• Received 27 June 2023
• Revised 8 January 2024
• Accepted 29 January 2024

DOI:https://doi.org/10.1103/PhysRevB.109.L081403

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Published by the American Physical Society