One-dimensional two-orbital SU(N) ultracold fermionic quantum gases at incommensurate filling: a low-energy approach

TL;DR

This paper analyzes the phase diagram of one-dimensional two-orbital SU(N) ultracold fermionic gases at incommensurate filling, revealing the formation of spectral gaps and novel superfluid states with bound states of 2N fermions.

Contribution

It provides a low-energy theoretical framework explicitly incorporating SU(N) symmetry to understand phases and instabilities in these ultracold atomic systems.

Findings

Spectral gap for nuclear-spin degrees of freedom is generally formed.

Multiple phases with different gapless modes are stabilized.

The dominant superfluid state involves bound states of 2N fermions, not pairing.

Abstract

We investigate the zero-temperature phase diagram of two-orbital SU(N) fermionic models at incommensurate filling which are directly relevant to strontium and ytterbium ultracold atoms loading into a one-dimensional optical lattice. Using a low-energy approach that takes into account explicitly the SU(N) symmetry, we find that a spectral gap for the nuclear-spin degrees of freedom is formed for generic interactions. Several phases with one or two gapless modes are then stabilized which describe the competition between different density instabilities. In stark contrast to the N=2 case, no dominant pairing instabilities emerge and the leading superfluid one is rather formed from bound states of 2N fermions.