  We discuss and compare the statistical properties of two stochastic
three-sphere micromachines, i.e., odd micromachine and thermal micromachine. We
calculate the steady state time-correlation functions for these micromachines
and decompose them into the symmetric and antisymmetric parts. In both cases,
the cross-correlation between the two spring extensions has an antisymmetric
part, which is a direct consequence of the broken time-reversal symmetry. For
the odd micromachine, the antisymmetric part of the correlation function is
proportional to the odd elasticity, whereas it is proportional to the
temperature difference between the two edge spheres for the thermal
micromachine. The entropy production rate and the Green-Kubo relations for the
two micromachines are also obtained. Comparing the results of the two models,
we argue an effective odd elastic constant of the thermal micromachine. The
effective odd elasticity of the thermal micromachine is proportional to the
temperature difference among the spheres, which causes an internal heat flow
and leads to directional locomotion in the presence of hydrodynamic
interactions.
