Single-Atom Heat Engine

In Germany, a group of men have devised a method for creating a single-atom heat engine as seen here, utilizing "an ion held within a modified linear Paul trap. [They] use laser cooing and electric-field noise to engineer cold and hot reservoirs. To determine the temperature of the ion, we make use of fast thermometry methods, which make use of the Doppler broadening of optical resonances. The thermodynamic cycles fo the engine is established for various temperature differences of the reservoirs, form which we deduce work and heat, and thus power output and efficiency. We additionally show that the work produced by the engine can be effectively stored and used to drive a harmonic oscillator against friction." The  heat engine is driven by alternately heating and cooling the ion in the radial direction by switching the electric noise on and off while the cooling laser is constantly running. To contain this oscillation, we provide adjustable damping by introducing an additional cooling laser in the axial direction. Optimal operation is achieved when an equilibrium is reached between the work generated by the engine and the energy dissipated by the damping.The group hope that their new technology will promote further exploration into devices and tools uncoupled with thermal reservoirs or single ion refrigerators and pumps. The group also hopes that this discovery will foster the exploration into small quantum machines. 

(A) Experimental setup composed of a single trapped ion (green); lasers for cooling, damping, and observation of the ion (blue); radio-frequency electrodes in funnel geometry (red); end caps (gold); and outer electrodes (gray). The position of the ion is imaged on an ICCD camera. Opposing voltage noise waveforms are additionally supplied to the outer electrodes so as to generate electric-field noise without affecting the trap frequencies.