Luttinger liquid of trimers in Fermi gases with unequal masses

Understand

We investigate one dimensional attractive Fermi gases in spin-dependent optical lattices.

• We show that three-body bound states - "trimers" - exist as soon as the two tunneling rates are different.
• We calculate the binding energy and the effective mass of a single trimer.
• We then show numerically that for finite and commensurate densities $n_\uparrow=n_\downarrow/2$ an energy gap appears, implying that the gas is a one-component Luttinger liquid of trimers with suppressed superfluid ordering.