Quantum Engine Smaller Than a Grain of Sand Built by Finnish Physicists

A Cyclic Quantum Heat Engine at the Nanoscale

According to НВ — Техно: Researchers at Aalto University in Finland have developed the world’s first cyclic quantum heat engine, embedded within a superconducting chip that is smaller than a grain of sand. Operating at temperatures near absolute zero, the device uses a transmon qubit as its working medium. The findings were published in Nature Communications, confirming that heat can be precisely controlled within a quantum processor chip.

Led by Academy Professor Mikko Möttönen, the team designed an engine where a transmon qubit is connected to a resonator and a quantum refrigerator. This setup allows the qubit to undergo heating, cooling, and energy conversion cycles based on the Otto cycle. The researchers ran the engine for up to three consecutive cycles, measuring power and efficiency that matched computer simulations. This marks the first experimental demonstration of a cyclic quantum heat engine built from superconducting circuits.

Why This Breakthrough Matters

While quantum heat engines have been demonstrated before using ion traps, atomic gases, nuclear spins, and diamond defects, this is the first time such a device has been realized on a superconducting platform. Researcher Tuomas Uusnäki explained: “In our experiment, we built a nanoscale heat engine from superconducting circuits and operated it in a cryostat near absolute zero. At its core is a transmon qubit, one of the fundamental building blocks of modern quantum technology.”

“Our quantum refrigerator can be tuned to either heat or cool the qubit as needed. Using precisely calculated control pulses, we ran the engine through the Otto cycle and monitored the qubit’s state during operation,” Uusnäki added. “This is the first experimental demonstration of a cyclic quantum heat engine on superconducting circuits. Using a single controllable quantum refrigerator as both the hot and cold bath simplifies the design and makes it more flexible.”

The team is now working toward a fully autonomous version of the quantum engine, which could have major implications for the future of quantum technologies. This research is significant because it shows how quantum components can be integrated into compact, energy-efficient systems. Superconducting circuits may open new possibilities in quantum computing and energy technology, potentially impacting fields from information processing to power systems. Developing self-contained quantum engines could simplify the practical implementation of complex quantum technologies.

This innovative development in quantum heat engines opens the door to further exploration of quantum mechanics. For instance, researchers are also investigating how to manipulate time within microscopic systems, which could have profound implications for the future of quantum technology. To learn more about this fascinating research, check out how physicists have found ways to halt and reverse time.