Quantum Spin Dynamics with Pairwise-Tunable, Long-Range Interactions

TL;DR

This paper introduces a versatile platform for simulating quantum magnetism with tunable, long-range pairwise interactions between spins in 1D and 2D lattices using atoms in photonic crystal waveguides, enabling exploration of complex quantum phenomena.

Contribution

The authors develop a method to precisely control spin-spin interactions at arbitrary distances, including phase and magnitude, using atomic states and photonic crystal waveguides, allowing simulation of complex quantum spin models.

Findings

Controlled long-range spin interactions demonstrated

Ability to engineer non-trivial Berry phases in spin lattices

Applicability to various well-known spin models

Abstract

We present a platform for the simulation of quantum magnetism with full control of interactions between pairs of spins at arbitrary distances in one- and two-dimensional lattices. In our scheme, two internal atomic states represent a pseudo-spin for atoms trapped within a photonic crystal waveguide (PCW). With the atomic transition frequency aligned inside a band gap of the PCW, virtual photons mediate coherent spin-spin interactions between lattice sites. To obtain full control of interaction coefficients at arbitrary atom-atom separations, ground-state energy shifts are introduced as a function of distance across the PCW. In conjunction with auxiliary pump fields, spin-exchange versus atom-atom separation can be engineered with arbitrary magnitude and phase, and arranged to introduce non-trivial Berry phases in the spin lattice, thus opening new avenues for realizing novel topological spin models. We illustrate the broad applicability of our scheme by explicit construction for several well known spin models.