Recent improvements in our understanding of how the principles of thermodynamics apply in the quantum realm could give a boost to quantum technology, and a clearer picture of quantum thermodynamics could in turn enhance our understanding of classical thermodynamics. Now, Aalto University researchers have demonstrated the first cyclic quantum heat engine inside a superconducting circuit.

Physicists have become increasingly fascinated with the idea that classical thermodynamics could be combined with quantum mechanics. Quantum mechanics captures the behavior of particles on tiny scales—smaller than atoms—while thermodynamics is about large systems, from molecules up to the entire universe. How do strange quantum phenomena like tunneling, entanglement and superposition mix with the stolid familiarity of the heat engines that kick-started the Industrial Revolution?

Heat engines, like James Watt’s famous steam engine, convert heat into useful energy, or work. They power our cars, ships and planes, and heat engines are how most power plants generate electricity. Now, the world’s first superconducting quantum heat engine has been built: a tiny device consisting of a transmon qubit, a resonator and a quantum refrigerator.