Single atom energy-conversion device with a quantum load

Understand

This work reports the functioning of a single atom energy-conversion device, operating either as a quantum engine or a refrigerator, coupled to a quantum load.

• The "working fluid" is comprised of two optical levels of a single ion, and the load is one vibrational mode of the same ion cooled down to the quantum regime.
• The energy scales of these two modes differ by 9 orders of magnitude.
• We realize cyclic energy transfers between the working fluid and the quantum load, either increasing or decreasing the population of the vibrational mode.