Quantum properties of a binary bosonic mixture in a double well

TL;DR

This paper analyzes the ground state properties of a two-component Bose-Hubbard model in a double-well potential, exploring quantum correlations, entanglement, and many-body states like Schrödinger cat states.

Contribution

It provides a detailed characterization of the ground state, including quantum correlations and entanglement, for variable intra- and inter-species interactions in a double-well system.

Findings

Identification of Schrödinger cat-like many-body states

Large von Neumann entropy indicating highly spread states

Quantification of entanglement between sites and species

Abstract

This work contains a detailed analysis of the properties of the ground state of a two-component two-sites Bose-Hubbard model, which captures the physics of a binary mixture of Bose-Einstein condensates trapped in a double-well potential. The atom-atom interactions within each species and among the two species are taken as variable parameters while the hopping terms are kept fixed. To characterize the ground state we use observables such as the imbalance of population and its quantum uncertainty. The quantum many-body correlations present in the system are further quantified by studying the degree of condensation of each species, the entanglement between the two sites and the entanglement between the two species. The latter is measured by means of the Schmidt gap, the von Neumann entropy or the purity obtained after tracing out a part of the system. A number of relevant states are identified, e.g. Schr\"odinger catlike many-body states, in which the outcome of the population imbalance of both components is completely correlated, and other states with even larger von Neumann entropy which have a large spread in Fock space.