The experiment demonstrates a quantum heat engine built from a transmon qubit in a superconducting circuit, using a quantum-circuit refrigerator as both heat source and sink to control heat flow on demand and extract work from ultracold energy fluctuations.

Operating at cryogenic temperatures inside a cryostat, the system executes a quantum Otto cycle with precisely timed microwave pulses, providing direct evidence of work extraction from the quantum state of the transmon.

Positive work output confirms theoretical models of quantum heat engines and shows functional operation in a quantum regime.

The work addresses a major bottleneck in scaling quantum computers by potentially reducing wiring complexity, noise, and cost from millions of external control cables connecting room-temperature electronics to cryogenic qubits.

Finland’s Quantum Technology Strategy targets around 1,000 logical qubits by 2035, underscoring the need for scalable quantum hardware and the potential benefits of autonomous quantum heat engines.

The work aligns with Finland’s strategy to envision quantum computers with thousands of logical qubits and emphasizes on-chip autonomy for quantum devices.

While practical power and efficiency are modest today, the setup offers a versatile test bed for quantum thermodynamics and points toward autonomous, on-chip thermal management for larger quantum machines.

Led by Mikko Möttönen and Tuomas Uusnäkki, the study was published in Nature Communications on July 13, 2026, and conducted at OtaNano, Finland, presenting a proof-of-concept that merges thermodynamics with quantum information science.

The approach could cut wiring and noise by enabling autonomous, on-chip heat management and cooling without relying on millions of external microwave cables.

This achievement shows the feasibility of engineering quantum thermodynamics in superconducting systems and sets groundwork for autonomous on-chip heat engines to stabilize future large-scale quantum computers.

An autonomous version of the quantum heat engine is being pursued to perform computing tasks on-chip and read neighboring qubits using internal thermal cycles, removing the need for extensive external control cables.

Future work aims to improve cooling, balance heating, and broaden cycles to enhance performance, while using the platform to study quantum coherence, interference, and non-adiabatic thermodynamic processes.