Enhanced repulsively bound atom pairs in topological optical lattice ladders

TL;DR

This paper explores how topological optical lattice ladders enhance bound atom pairs and facilitate pair superfluidity, revealing new phases and preparation methods relevant for quantum simulation.

Contribution

It demonstrates the role of lattice topology in strengthening bound pairs and introduces schemes for preparing and detecting pair superfluid and supersolid phases.

Findings

Lattice topology enhances effective pair-tunnelling.

Identification of robust pair superfluidity in topological ladders.

Proposal of schemes for phase preparation and detection.

Abstract

There is a growing interest in using cold-atom systems to explore the effects of strong interactions in topological band structures. Here we investigate interacting bosons in a Cruetz ladder, which is characterised by topological flat energy bands where it has been proposed that interactions can lead to the formation of bound atomic pairs giving rise to pair superfluidity. By investigating realistic experimental implementations, we understand how the lattice topology enhances the properties of bound pairs giving rise to relatively large effective pair-tunnelling in these systems which can lead to robust pair superfluidity, and we find lattice supersolid phases involving only pairs. We identify schemes for preparation of these phases via time-dependent parameter variation and look at ways to detect and characterise these systems in a lattice. This work provides a starting point for investigating the interplay between the effects of topology, interactions and pairing in more general systems, with potential future connections to quantum simulation of topological materials.