Fermion pairing in body-centered-cubic quantum simulators of extended Hubbard models

TL;DR

This paper explores fermion pair formation and condensation in BCC optical lattices simulating extended Hubbard models, predicting small, light pairs with high binding energies and potential Bose-Einstein condensation at ultra-low temperatures.

Contribution

It provides theoretical predictions on fermion pairing properties and transition temperatures in BCC optical lattices for extended Hubbard models, a novel insight for quantum simulation.

Findings

Local pairs form with large binding energies.

Pairs are small and light when onsite and intersite attractions are similar.

$^6$Li atom pairs Bose-Einstein condense around 10 nK.

Abstract

We investigate formation and condensation of fermion pairs in cold-atom quantum simulators for extended Hubbard models ($UV$ models) with body-centered-cubic (BCC) optical lattices in the dilute limit, predicting small and light pairs. Pair mass, radius, and binding conditions are calculated, and used to compute transition temperatures. We predict that: (a) local pairs form in BCC optical lattices and binding energies can be large; (b) for particular cases where onsite $U$ and intersite $V$ are attractive with similar size, pairs are both small and light; and (c) pairs of $^6$Li atoms Bose--Einstein condense at temperatures of around 10 nK.