https://phys.org/news/2018-07-qubits-valves-quantum.html > "We have realised a miniature heat valve in a quantum system composed of an artificial atom, a superconducting qubit—the basic building block of both quantum computing and quantum heat engines," explains Professor Pekola. > In quantum computers, the qubit has to be decoupled from the noisy external world to sustain a fragile quantum state, but in quantum heat engines, the system needs to be coupled to its dissipative surroundings in the form of heat baths. A particularly puzzling problem is the process of thermalisation when connecting external heat sources or 'thermal baths' to a coherent quantum system or qubit. Ultimately, heat is exchanged between these systems through the emission of photons.