World’s First Superconducting Quantum Heat Engine Could Help Unlock Massive Quantum Computers

## A New Era in Quantum Thermodynamics Scientists have long been fascinated by the intersection of quantum mechanics and thermodynamics. The two fields normally describe very different scales, with quantum mechanics explaining the behavior of matter at extremely small scales and thermodynamics describing how heat and energy behave in much larger systems. However, by bringing these two areas together, researchers can gain a deeper understanding of thermodynamic processes in the quantum world. ## A Heat Engine Built for the Quantum World Conventional heat engines, such as James Watt's steam engine, are well-known for their ability to turn heat into useful work. However, these engines operate on a much larger scale than the quantum world. The researchers at Aalto University have now created the world's first superconducting quantum heat engine, which combines a transmon qubit, a resonator, and a quantum refrigerator to operate under ultracold quantum conditions. The engine was able to use the tiny amount of available heat to repeatedly produce positive work, achieving a cyclic operation that has been an important objective for researchers working on quantum heat engines. This result provides a proof of concept for superconducting heat engines that could eventually contribute to improved quantum computing technology. ## Toward Autonomous Quantum Computer Hardware The researchers are now trying to improve the design and eventually develop a fully autonomous heat engine. One possible use would be reading out qubits without having to carry a microwave pulse from millikelvin temperatures all the way to room temperature. This capability could become especially valuable as quantum computers grow, as autonomous devices integrated directly into superconducting circuits could reduce both the cost and complexity of machines containing very large numbers of qubits. The pioneering experiment was carried out using OtaNano, Finland's national research infrastructure for nano, micro, and quantum technology. Funding came from the Research Council of Finland and the Finnish Cultural Foundation. The development of a superconducting quantum heat engine has the potential to unlock massive quantum computers, making them easier to build and more efficient. As researchers continue to improve the design and functionality of these engines, we can expect to see significant advancements in the field of quantum computing.