High temperature thermodynamics of fermionic alkaline earth atoms in optical lattices

TL;DR

This paper models the thermodynamics of fermionic alkaline earth atoms in optical lattices using the SU(N) Hubbard model, revealing that increasing N leads to significantly colder Mott insulators under experimental conditions.

Contribution

It provides an accurate calculation of thermodynamic properties and final temperatures, highlighting the cooling effect of larger N in ultracold atom experiments.

Findings

Increasing N results in substantially colder Mott insulators.

Final temperatures depend on initial entropy and lattice parameters.

Cooling effect persists for all N up to approximately 20.

Abstract

We calculate experimentally relevant properties of trapped fermionic alkaline earth atoms in an optical lattice, modeled by the SU(N) Hubbard model. Our calculation is accurate when the temperature is much larger than the tunneling rate, similar to current regimes in ultracold atom experiments. In addition to exploring the Mott insulator-metal crossover, we calculate final temperatures achieved by the standard experimental protocol of adiabatically ramping from a non-interacting gas, as a function of initial gas temperature and final state lattice parameters. Of particular experimental interest, we find that increasing $N$ gives substantially \textit{colder} Mott insulators, up to more than a factor of five for relevant parameters. This cooling happens for all $N$, fixing the initial entropy, or for all $N \lsim 20$ (the exact value depends on dimensionality), fixing the initial temperature.