Spin-1 Atoms in Optical Superlattices: Single-Atom Tunneling and Entanglement

TL;DR

This paper theoretically investigates spin-1 Bose-Einstein condensates in optical superlattices, focusing on single-atom tunneling, magnetic order, and bipartite entanglement, revealing how spin effects influence quantum behaviors in mesoscopic systems.

Contribution

It introduces a model for spin-1 bosons in optical superlattices that accounts for spin-dependent tunneling and entanglement, highlighting magnetic order and quantum correlations.

Findings

Spin-dependent effects qualitatively alter tunneling events.

Different magnetic orders emerge depending on double well asymmetry.

Orbital and spin entanglement contributions sum to a lower bound of total entanglement.

Abstract

We examine spinor Bose-Einstein condensates in optical superlattices theoretically using a Bose-Hubbard Hamiltonian that takes spin effects into account. Assuming that a small number of spin-1 bosons is loaded in an optical potential, we study single-particle tunneling that occurs when one lattice site is ramped up relative to a neighboring site. Spin-dependent effects modify the tunneling events in a qualitative and quantitative way. Depending on the asymmetry of the double well different types of magnetic order occur, making the system of spin-1 bosons in an optical superlattice a model for mesoscopic magnetism. We use a double-well potential as a unit cell for a one-dimensional superlattice. Homogeneous and inhomogeneous magnetic fields are applied and the effects of the linear and the quadratic Zeeman shifts are examined. We also investigate the bipartite entanglement between the sites and construct states of maximal entanglement. The entanglement in our system is due to both orbital and spin degrees of freedom. We calculate the contribution of orbital and spin entanglement and show that the sum of these two terms gives a lower bound for the total entanglement.