  We study the heat transfer between two nanoparticles held at different
temperatures that interact through nonreciprocal forces, by combining molecular
dynamics simulations with stochastic thermodynamics. Our simulations reveal
that it is possible to construct nano refrigerators that generate a net heat
transfer from a cold to a hot reservoir at the expense of power exerted by the
nonreciprocal forces. Applying concepts from stochastic thermodynamics to a
minimal under-damped Langevin model, we derive exact analytical expressions
predictions for the fluctuations of work, heat, and efficiency, which reproduce
thermodynamic quantities extracted from the molecular dynamics simulations. The
theory only involves a single unknown parameter, namely an effective friction
coefficient, which we estimate fitting the results of the molecular dynamics
simulation to our theoretical predictions. Using this framework, we also
establish design principles which identify the minimal amount of entropy
production that is needed to achieve a certain amount of uncertainty in the
power fluctuations of our nano refrigerator. Taken together, our results shed
light on how the direction and fluctuations of heat flows in natural and
artificial nano machines can be accurately quantified and controlled by using
nonreciprocal forces.
