Effective spin-spin interactions in bilayers of Rydberg atoms and polar molecules

TL;DR

This paper proposes a method to realize tunable indirect spin-spin interactions in bilayer systems of polar molecules and Rydberg atoms trapped in optical lattices, enabling simulation of complex quantum spin models.

Contribution

It introduces a scheme to engineer effective spin interactions mediated by Rydberg atoms or polar molecules in optical lattices, including frustrated XXZ models with variable interaction signs.

Findings

Realization of indirect XX, Ising, and XXZ interactions with tunable coefficients.

Implementation of the J1-J2 XXZ model with frustration.

Control over interaction sign and strength via interspin distance.

Abstract

We show that indirect spin-spin interactions between effective spin-1/2 systems can be realized in two parallel 1D optical lattices loaded with polar molecules and/or Rydberg atoms. The effective spin can be encoded into low-energy rotational states of polar molecules or long-lived states of Rydberg atoms, tightly trapped in a deep optical lattice. The spin-spin interactions can be mediated by Rydberg atoms, placed in a parallel shallow optical lattice, interacting with the effective spins by charge-dipole (for polar molecules) or dipole-dipole (for Rydberg atoms) interaction. Indirect XX, Ising and XXZ interactions with interaction coefficients $J^{\bot}$ and $J^{zz}$ sign varying with interspin distance can be realized, in particular, the $J_{1}-J_{2}$ XXZ model with frustrated ferro-(antiferro-)magnetic nearest (next-nearest) neighbor interactions.