Correlated hopping of bosonic atoms induced by optical lattices

TL;DR

This paper investigates how asymmetries in contact interactions in ultracold atoms trapped in state-dependent lattices lead to correlated hopping phenomena, revealing various quantum phases including Mott insulators, charge density waves, and a novel pair superfluid.

Contribution

It introduces an effective Hamiltonian capturing correlated hopping induced by interaction asymmetries and characterizes the resulting quantum phases and phase transitions.

Findings

Weak correlated hopping yields Mott insulators and charge density waves.

Strong correlated hopping leads to a pair superfluid phase.

The pair superfluid phase persists over a wide range of interaction asymmetries.

Abstract

In this work we analyze a particular setup with ultracold atoms trapped in state-dependent lattices. We show that any asymmetry in the contact interaction translates into one of two classes of correlated hopping. After deriving the effective lattice Hamiltonian for the atoms, we obtain analytically and numerically the different phases and quantum phase transitions. We find for weak correlated hopping both Mott insulators and charge density waves, while for stronger correlated hopping the system transitions into a pair superfluid. We demonstrate that this phase exists for a wide range of interaction asymmetries and has interesting correlation properties that differentiate it from an ordinary atomic Bose-Einstein condensate.