Aalto University researchers demonstrate world's first superconducting quantum heat engine

August 14, 2026 at 05:00 AM1 min

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Researchers at Aalto University have demonstrated the first cyclic quantum heat engine built inside a superconducting circuit, and the results appear in Nature Communications. The device combined a transmon qubit, a resonator and a quantum refrigerator, and produced positive work under ultracold conditions. Unlike a conventional heat engine, the same quantum refrigerator supplied both heating and cooling.

Key Facts

The study was led by Academy Professor Mikko Möttönen and published in Nature Communications.
The device combined a transmon qubit, a resonator and a quantum refrigerator.
The researchers recreated an Otto cycle inside a superconducting circuit, the thermodynamic process used in car engines.
First author Tuomas Uusnäkki said the engine was operated in a cryostat near absolute zero.

The Superconducting Engine

Researchers at Aalto University have built the world's first superconducting quantum heat engine. The device combines a transmon qubit, a resonator and a quantum refrigerator. Under ultracold quantum conditions, the engine repeatedly produced positive work from the tiny amount of available heat. Achieving this kind of cyclic operation has been an important objective for researchers working on quantum heat engines. The study, led by Academy Professor Mikko Möttönen, was published in Nature Communications.

Otto Cycle Near Absolute Zero

The researchers reproduced an Otto cycle inside a superconducting circuit. The Otto cycle is a thermodynamic process also used in car engines and other conventional machines. First author Tuomas Uusnäkki said the nanofabricated heat engine was operated in a cryostat near absolute zero. The researchers connected the transmon qubit, one of the basic building blocks of modern quantum technologies, to a quantum circuit refrigerator. The same quantum refrigerator supplied both heating and cooling, unlike a conventional heat engine that relies on separate hot and cold environments.