Pair correlations as a signature of entanglement: A bosonic mixture in gauge field ring lattices

Instituto de Física, Pontificia Universidad Católica de Chile - Casilla 306, Santiago 22, Chile

Received: 29 January 2016
Accepted: 17 August 2016

Abstract

We study the pair-superfluid phase and entanglement of a Bose-Bose mixture of ultracold atoms in a ring lattice in the presence of a synthetic gauge field. Special attention is given to a quantum phase transition region of the phase diagram observed in the parameter space that characterizes the intra- and inter- species interactions of the system. In the scenario of large interaction, it is shown that the ground and excited states of the lowest-energy band exhibit features of a pair-superfluid phase. We demonstrate that in the subspace associated with the lowest-energy band there is a maximally entangled eigenstate that is a perfect pair-superfluid. We suggest to use this connection between the bipartite entanglement and the pair-superfluidity as a signature of the presence of entanglement in the eigenstates associated with the lowest-energy band. Moreover, we find strong indications that the interference pattern of the pair-superfluid phase in momentum space can be used as a tool for the characterization of the entanglement in the ground state.