Ultra-efficient LED puts out more power than is pumped in

The LED produces 69 picowatts of light using 30 picowatts of power, giving it an efficiency of 230 percent. That means it operates above “unity efficiency” — putting it into a category normally occupied by perpetual motion machines.

As the article goes on to explain, the LED doesn’t actually violate conservation of energy, because the LED is tapping into the thermal energy present, as manifested in lattice vibrations i.e. there is a conversion of phonons to photons occurring, which means that the LED is acting as a heat engine (a term that’s not mentioned until the last paragraph). However, efficiency isn’t typically used in this context because it’s misleading; what you discuss is the coefficient of performance: how much energy do you move around vs how much energy you put in, because for a given energy input, you can deliver/remove many times that energy to/from your target. This is what heat pumps do and why they are used.

The neat thing here is that the rejected heat from the LED is light, which is pretty neat. At such low powers (tens of picoWatts) this is not yet a usable light source, so there is a question of whether it can scale, and as mentioned, there is the possibility of using this as a cooling component for small-scale devices.