Caloric effects in an open Fermi–Hubbard optical dimer due to onsite and heat bath-induced two-particle interactions

The immersion of the Fermi–Hubbard optical dimer in a mean field Fermi gas, acting as a heat bath, modifies the behavior of the statistical mechanical properties of the particles trapped in it. This is done by varying the two-particle interactions induced by the heat bath and the onsite two-particle interaction <em>U</em>. It is shown that in the presence of the heat bath-induced interaction, the partition function <em>Z</em> drops to a minimum finite value in the repulsive regime of <em>U</em> at the normalized temperature region <em>kT</em> ≲ <em>t/</em>2, where <em>t</em> is the tunneling parameter. In this temperature region, the convergence points of the respective isolines of the entropy <em>S</em> and the heat capacity <em>Cᵥ</em> move towards each other. Such shift in their features finetune <em>S</em> and <em>Cᵥ</em> relative to their behavior in the absence of two-particle interactions with the bath.