A pot on a stove receives heat, but not work: the gas under the lid just heats up. But what if the stove is not ordinary, but quantum? Then heat and work can arrive simultaneously, like from an engine that also heats.
In a new study, exactly this case is described: a classical system (say, a pendulum or a small mirror) bathes in a quantum environment. This environment is not just "hot water," but an active intermediary: it transfers energy and can immediately take it back, performing mechanical work. The researchers derived rules for calculating heat, work, and the increase of disorder (entropy) in such a semiclassical picture.
An example from the paper is optomechanics: light in a cavity pushes on a mirror, making it vibrate. This vibrating light is not just random noise, but a quantum reservoir that both heats the mirror and pushes it. Such a scheme is already used in ultrasensitive detectors.
The takeaway is simple: even quantum chaos obeys rules if you correctly count where heat is and where work is. And then "just noise" turns out to be a useful resource.
In optomechanics, light can cool a mirror to thousandths of a degree above absolute zero by simply "sucking out" its vibrations.
In Arthur C. Clarke's novel "The Light of Other Days," quantum fluctuations of the vacuum are used as an energy source for instantaneous communication.