Momentum-selective pair creation of spin excitations in dipolar bilayers

TL;DR

This paper predicts a momentum-dependent dynamic instability in a dipolar bilayer system, leading to rapid creation of spin excitation pairs with tunable momentum distributions, observable in current quantum simulation experiments.

Contribution

It introduces a novel mechanism for pair creation of spin excitations driven by dipolar interactions in a bilayer system, with controllable momentum characteristics.

Findings

Exponential growth of spin excitation pairs at specific momenta

Tunable momentum distribution via dipolar orientation and layer separation

Observable effects at low filling fractions in current experimental setups

Abstract

We study the temporal growth and spatial propagation of quantum correlations in a two-dimensional bilayer realising a spin-1/2 quantum XXZ model with couplings mediated by long-range and anisotropic dipolar interactions. Starting with an initial state consisting of spins with opposite magnetization in each of the layers, we predict the emergence of a momentum-dependent dynamic instability in the spin structure factor that results, at short times, in the creation of pairs of excitations at exponentially fast rates. The created pairs present a characteristic momentum distribution that can be tuned by controlling the dipolar orientation, the layer separation or the dipolar couplings. The predicted behavior remains observable at very low filling fractions, making it accessible in state-of-the-art experiments with Rydberg atoms, magnetic atoms, and polar molecule arrays.